Audio device, sound processing method, sound processing program, sound output method, and sound output program

ABSTRACT

There is provided an audio device including a control section configured to cause an audio signal to be output, the audio signal including a sound signal obtained through playback of content and a sound signal received from a communication partner device, and a sound processing section configured to generate an elimination signal obtained by eliminating a given sound signal from a microphone detection signal, which is the audio signal that is propagated and detected by a microphone. The control section causes the communication partner device to transmit the elimination signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Priority PatentApplication JP 2014-023340 filed Feb. 10, 2014, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an audio device, a sound processingmethod, a sound processing program, a sound output method, and a soundoutput program.

There has recently appeared a system for carrying out a conversationwith a partner while transmitting and receiving a sound between aplurality of terminals. In such a system, a telephonic communicationsound from a terminal of a telephonic communication source reaches aterminal of a telephonic communication destination while beingattenuated and causing a delay time. Further, the telephoniccommunication sound is detected by a microphone of the terminal of thetelephonic communication destination, and is returned to the terminal ofthe telephonic communication source while being attenuated and causing adelay time. In this way, since the telephonic communication sound goesand comes back between the terminals while being attenuated and causinga delay time, there may occur a phenomenon that the sound to which anecho is added may be output from a terminal.

In order to reduce the occurrence of such a phenomenon, even when asound transmitted from the terminal of the telephonic communicationsource is output from the speaker and is detected by the microphone, theterminal of the telephonic communication destination may cancel thesound to thereby not to transmit the sound to the terminal of thetelephonic communication source, which is called echo cancellation maybe performed (for example, see JP 2013-038763A). It is generally knownthat if the telephonic communication sound is prevented from going andcoming back between the terminals by such an echo cancellation, acomfortable conversation can be carried out.

SUMMARY

However, in the case where a conversation is carried out while listeningto a content playback sound, for example, the terminal of the telephoniccommunication destination not only outputs a conversation sound of thetelephonic communication source but also a content playback sound of thetelephonic communication source from the speaker. As a result, since thecontent playback sound also goes and comes back between the terminalswhile being attenuated and causing a delay time, the sound to which anecho is added may be output from a terminal and there may occur aphenomenon that it is difficult to carry out a conversation comfortablywith a partner.

In light of the foregoing, it is desirable to provide technology capableof making a conversation carried out with a partner while listening to acontent playback sound more comfortable.

According to an embodiment of the present disclosure, there is providedan audio device including a control section configured to cause an audiosignal to be output, the audio signal including a sound signal obtainedthrough playback of content and a sound signal received from acommunication partner device, and a sound processing section configuredto generate an elimination signal obtained by eliminating a given soundsignal from a microphone detection signal, which is the audio signalthat is propagated and detected by a microphone. The control sectioncauses the communication partner device to transmit the eliminationsignal.

According to another embodiment of the present disclosure, there isprovided a sound processing method including causing an audio signal tobe output, the audio signal including a sound signal obtained throughplayback of content and a sound signal received from a communicationpartner device, generating an elimination signal obtained by eliminatinga given sound signal from a microphone detection signal, which is theaudio signal that is propagated and detected by a microphone, andcausing, by a processor, the communication partner device to transmitthe elimination signal.

According to another embodiment of the present disclosure, there isprovided a sound processing program for causing a computer to functionas an audio device, the audio device including a control sectionconfigured to cause an audio signal to be output, the audio signalincluding a sound signal obtained through playback of content and asound signal received from a communication partner device, and a soundprocessing section configured to generate an elimination signal obtainedby eliminating a given sound signal from a microphone detection signal,which is the audio signal that is propagated and detected by amicrophone. The control section causes the communication partner deviceto transmit the elimination signal.

According to another embodiment of the present disclosure, there isprovided an audio device including a control section configured to, whenan audio signal including a sound signal obtained through playback ofcontent and a sound signal received from a communication partner deviceis input from another audio device, cause the audio signal to be outputfrom a speaker. The another audio device generates an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone.

According to another embodiment of the present disclosure, there isprovided a sound output method including causing, when an audio signalincluding a sound signal obtained through playback of content and asound signal received from a communication partner device is input fromanother audio device, the audio signal to be output from a speaker. Theanother audio device generates an elimination signal obtained byeliminating a given sound signal from a microphone detection signal,which is the audio signal that is propagated and detected by amicrophone.

According to another embodiment of the present disclosure, there isprovided a sound output program for causing a computer to function as anaudio device, the audio device including a control section configuredto, when an audio signal including a sound signal obtained throughplayback of content and a sound signal received from a communicationpartner device is input from another audio device, cause the audiosignal to be output from a speaker. The another audio device generatesan elimination signal obtained by eliminating a given sound signal froma microphone detection signal, which is the audio signal that ispropagated and detected by a microphone.

According to one or more of embodiments of the present disclosure, thereis provided technology capable of making a conversation carried out witha partner while listening to a content playback sound more comfortable.Note that the effects described above are not necessarily limitative.With or in the place of the above effects, there may be achieved any oneof the effects described in this specification or other effects that maybe grasped from this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a basic configuration example of an AVsystem;

FIG. 2 is a diagram showing a CEC table indicating correspondencerelationship between a device and a CEC logical address;

FIG. 3 is a block diagram showing a configuration example of atelevision receiver (sink device) that configures the AV system;

FIG. 4 is a block diagram showing a configuration example of an AVamplifier that configures the AV system;

FIG. 5 is a block diagram showing a configuration example of a set-topbox (source device) that configures the AV system;

FIG. 6 is a block diagram showing a configuration example of an HDMItransmission section (HDMI source) and an HDMI reception section (HDMIsink);

FIG. 7 is a diagram showing a block configuration of data transmittedthrough a CEC line (CEC channel);

FIG. 8 is a diagram showing an example of data structure of a headerblock;

FIG. 9 is a diagram showing an overall configuration example of acommunication system;

FIG. 10 is a diagram showing a layout example of a screen displayed on adisplay panel by a television receiver;

FIG. 11 is a diagram showing a flow of a sound in a case of a single TV;

FIG. 12 is a diagram illustrating a configuration related to echocancellation processing in a case of the single TV;

FIG. 13 is a diagram showing an example of an adaptive filtercoefficient obtained by learning;

FIG. 14 is a flowchart showing a flow of an operation of the echocancellation processing in the case of the single TV;

FIG. 15 is a diagram showing a flow of video data and audio data atnormal times in a case of an external amplifier;

FIG. 16 is a diagram showing a flow of video data and audio data at atime of cancellation interlocking state in the case of the externalamplifier;

FIG. 17 is a diagram illustrating a configuration related to echocancellation processing in the case of the external amplifier;

FIG. 18 is a diagram illustrating a case where video data and sound dataoutput from a digital tuner are viewed and listened to;

FIG. 19 is a diagram illustrating a case where video data and sound dataoutput from a set-top box used as an example of a source device areviewed and listened to;

FIG. 20 is a diagram illustrating an example of switching betweengeneral two-screen mode/non-two-screen mode;

FIG. 21 is a diagram showing an example of information notificationperformed between the television receiver and the AV amplifier;

FIG. 22 is a diagram illustrating switching of sound fields;

FIG. 23 is a sequence diagram showing an overall flow of an operation ofthe communication system while a TV is being watched;

FIG. 24 is a sequence diagram showing an overall flow of an operation ofthe communication system while a STB is being watched;

FIG. 25 is a sequence diagram showing a flow of an operation of thecommunication system at a time of starting telephonic communication anda time of ending telephonic communication;

FIG. 26 is a flowchart showing a flow of an operation of echocancellation processing (with delay amount notification) in the case ofthe external amplifier;

FIG. 27 is a flowchart showing a flow of an operation performed by theAV amplifier at a time of receiving an echo cancellation start request;

FIG. 28 is a flowchart showing a flow of an operation performed by theAV amplifier at a time of starting interlocking operations with the echocancellation;

FIG. 29 is a flowchart showing a flow of an operation performed by theAV amplifier at a time of receiving an echo cancellation end request;

FIG. 30 is a flowchart showing a flow of an operation performed by theAV amplifier at a time of ending interlocking operations with the echocancellation;

FIG. 31 is a sequence diagram showing a flow of an overall operation ofthe communication system in a case where a sound delay amount is changedin the AV amplifier;

FIG. 32 is a flowchart showing a flow of an operation performed by theAV amplifier in the case where the sound delay amount is changed in theAV amplifier;

FIG. 33 is a sequence diagram showing a flow of an operation of thecommunication system in a case where interlocking with the echocancellation is interrupted by a state change in the AV amplifier;

FIG. 34 is a flowchart showing a flow of an operation of echocancellation processing (with interruption of echo cancellation) in thecase of the external amplifier;

FIG. 35 is a flowchart showing a flow of an operation of the AVamplifier in a case where operation conditions are changed;

FIG. 36 is a flowchart showing a flow of an operation of determininginterlock capability with echo cancellation performed in the AVamplifier;

FIG. 37 is a sequence diagram showing an operation example of thecommunication system in a case where sound output is changed from thetelevision receiver to the AV amplifier during telephonic communication;

FIG. 38 is a sequence diagram showing an operation example of thecommunication system in a case where sound output is changed from the AVamplifier to the television receiver during telephonic communication;

FIG. 39 is a sequence diagram showing an operation example of thecommunication system in a case where a volume of the AV amplifier ischanged; and

FIG. 40 is a flowchart showing a flow of an operation of echocancellation processing (with volume notification) in the case of theexternal amplifier.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Further, in this specification and the appended drawings, there are somecases where multiple structural elements that have substantially thesame function and structure are distinguished from one another by beingdenoted with different alphabets or numerals after the same referencenumeral. Note that, in the case where it is not necessary to distinguishthe multiple structural elements that have substantially the samefunction and structure from one another, the multiple structuralelements are denoted with the same reference numeral only.

Note that the description will be given in the following order.

1. Description of HDMI standard

2. Description of embodiment

-   -   2-1. Configuration example of AV system    -   2-2. Configuration example of communication system    -   2-3. Flow of operation of communication system

3. Conclusion

1. Description of HDMI Standard

First, the HDMI standard that may be applied to an AV system (devicecontrol apparatus) according to an embodiment of the present disclosurewill be described. In recent years, a high definition multimediainterface (HDMI) has been in widespread use as a digital interface fortransmitting a video signal (image signal) and a sound signal (audiosignal). HDMI is an interface having a sound transmitting function and acopyright protecting function in addition to the digital visualinterface (DVI) standard, which is a standard of connection between apersonal computer (PC) and a display, and is arranged for audio visual(AV) devices. The detail of the HDMI standard is described in“High-Definition Multimedia Interface Specification Version 1.4”, forexample.

Further, an interface of the HDMI standard is capable of performingbidirectional transmission of a control signal. Accordingly, forexample, in the interface of the HDMI standard, the control signal maybe transmitted from a television receiver to an output apparatusconnected to the television receiver by an HDMI cable, such as a set topbox (STB) or a video disc player. In this way, the control signal istransmitted by the television receiver, and thus, a user can control anentire AV system using a remote control of the television receiver. Notethat the signals transmitted using a transmission cable of the HDMIstandard include, in addition to control instruction for controlling thedevice, a response to the instruction and a signal indicating the stateof the device, and those signals are each collectively referred to ascontrol signal in this specification.

In the HDMI standard, inter-device control using consumer electronicscontrol (CEC) is defined. The CEC is one transmission line prepared inthe HDMI standard, and performs bidirectional data transmission. Usingthis CEC line, various controls can be performed based on uniquephysical and logical addresses assigned to respective devices present inan HDMI network. For example, if play-back is performed by a video discplayer connected by the HDMI cable to a television receiver when a useris viewing digital broadcast on the television receiver, the televisionreceiver is automatically switched to an input connected to the videodisc player. Also, a menu displayed in the video disc player and ON/OFFof the power can be controlled by using a remote control of thetelevision receiver.

Further, as shown in FIG. 2, when each device present in an HDMI networkis recognized as a CEC-compatible device corresponding to an assignedlogical address, an operation on the recognized CEC-compatible devicecan be performed.

In the HDMI-CEC standard, <Active Source> is defined as a CEC message toindicate the device having images displayed in the television receiver.According to the definition, for example, when a user operates aplayback button of a video disc player compatible with the HDMIstandard, the video disc player outputs an AV stream if the playeritself is in a state (i.e., active state) of being capable of outputtingstable video signals. Further, the video disc player broadcasts an<Active Source> message indicating that the video disc player is anactive device.

Here, “broadcast” refers to simultaneous transmission of signals to alldevices, not to a specific device. The television receiver and the otherexternal devices that have received the broadcasted <Active Source>message switch paths to play back the AV stream output from the videodisc player.

In this way, the HDMI-CEC standard defines that a device which startsdisplaying a video in the television receiver broadcasts an <ActiveSource> message to the other devices in the network. The <Active Source>message is one of CEC messages defined in the HDMI standard.

Heretofore, there has been described the HDMI standard that may beapplied to the AV system according to an embodiment of the presentdisclosure.

2. Description of Embodiment

Subsequently, an embodiment of the present disclosure will be described.Technology according to the present disclosure may be executed invarious modes.

<2-1. Configuration Example of AV System>

First, there will be described a configuration example of an AV systemthat may be applied to an embodiment of the present disclosure. FIG. 1is a block diagram showing a configuration example of an AV system.

The AV system 100 includes a television receiver 200, an AV amplifier300, and a set top box 400. The set top box 400 configures an HDMIsource device. The AV amplifier 300 configures an HDMI repeater device.The television receiver 200 configures an HDMI sink device. The set topbox 400 is a device which receives broadcast signals and converts thebroadcast signals into signals viewable on the television receiver 200.

The television receiver 200 is a CEC-compatible device, and includesHDMI terminals 201 and 202, and an optical output terminal 203. Thetelevision receiver 200 has a configuration that can be remotelycontrolled by a remote control (not shown). The television receiver 200has a function of executing a process based on an application anddisplaying given information, or controlling a device connected to thetelevision receiver 200 at the HDMI terminals 201 and 202.

The set top box 400 includes an HDMI terminal 401, and is aCEC-compatible device.

The AV amplifier 300 is a CEC-compatible device, and includes HDMIterminals 301, 302, 303, and 304, and an optical input terminal 305. Tothe AV amplifier 300, a speaker set is provided, and it is configuredsuch that an audio signal that is playback-processed in the AV amplifier300 is output from the speaker set. The AV amplifier 300 and the speakerset may be connected to each other via wire or radio.

The television receiver 200 and the AV amplifier 300 are connected viaan HDMI cable 701 and an optical cable 702. That is, one end of the HDMIcable 701 is connected to the HDMI terminal 201 of the televisionreceiver 200 and the other end thereof is connected to the HDMI terminal304 of the AV amplifier 300. One end of the optical cable 702 isconnected to the optical output terminal 203 of the television receiver200 and the other end thereof is connected to the optical input terminal305 of the AV amplifier 300.

Further, the AV amplifier 300 and the set top box 400 are connected viaan HDMI cable 703. That is, one end of the HDMI cable 703 is connectedto the HDMI terminal 301 of the AV amplifier 300, and another end isconnected to the HDMI terminal 401 of the set top box 400.

(Acquisition of Physical Address and Logical Address)

In the AV system 100 shown in FIG. 1, a physical address and a CEClogical address of each device are acquired, for example, as follows.

That is, when the AV amplifier 300 is connected to the televisionreceiver 200 (the physical address is and the CEC logical address is{0}) via the HDMI cable 701, the AV amplifier 300 acquires the physicaladdress from the television receiver 200 using an HDMI control protocol.

The CEC-compatible device is defined to acquire a logical address uponHDMI connection. The CEC-compatible device performs message transmissionand reception using this logical address.

FIG. 2 is a diagram showing a table indicating a correspondencerelationship between a device and a CEC logical address. A device “TV”is a device for displaying a video from a television receiver, aprojector, and the like. A device “recording device” is a recordingdevice such as a hard disk recorder or a DVD recorder. A device “tuner”is a device for receiving AV content, such as a set top box (STB) thatreceives a cable television broadcast. A device “playback device” is aplayer device such as a video player or a camcorder. A device “audiosystem” is an audio processing device such as an AV amplifier.

The AV amplifier 300 is a CEC-compatible device, as described above. TheAV amplifier 300 decides a logical address {5} as “Audio System” basedon the table of FIG. 2. In this case, the AV amplifier 300 recognizesthat a device having this logical address {5} is not included in theother devices with a <Polling Message> of the CEC control protocol andthen decides the logical address {5} as its logical address. The AVamplifier 300 notifies other devices such as the television receiver 200that the device which has acquired the physical address has acquired thelogical address {5} by the CEC-compatible device by means of a <ReportPhysical Address> of the CEC control protocol.

When the set top box 400 is connected to the AV amplifier 300 via theHDMI cable 703, the set top box 400 acquires a physical address from theAV amplifier 300 using the HDMI control protocol.

The set top box 400 is a CEC-compatible device, as described above. Theset top box 400 decides logical address {3} as a “Tuner 1” based on thetable of FIG. 2. In this case, the set top box 400 recognizes that adevice having this logical address {3} is not included in the otherdevices with a <Polling Message> of the CEC control protocol and thendecides the logical address {1} as its logical address. The set top box400 notifies the television receiver 200 and the AV amplifier 300 thatthe device which has acquired the physical address has acquired thelogical address {3} by the CEC-compatible device by means of the <ReportPhysical Address> of the CEC control protocol.

(Playback of Video Signal and Sound Signal)

When a program (content) tuned by a tuner of the television receiver 200is to be viewed in the AV system 100 shown in FIG. 1, the followingoperation is executed. That is, an image by a video signal obtained bythe tuner is displayed on a display panel (not shown) of the televisionreceiver 200. An audio (sound) by an audio signal obtained by the tuneris output from speakers (not shown) of the television receiver 200 whenthe AV amplifier 300 is in a system audio mode of OFF. When the systemaudio mode is ON, the audio by the audio signal obtained by the tuner isoutput from the speaker set provided to the AV amplifier 300.

The audio signal obtained by the tuner of the television receiver 200becomes, for example, an optical digital audio signal and is supplied tothe AV amplifier 300 via the optical cable 702. Further, the ON/OFF ofthe system audio mode in the AV amplifier 300 may be set by a useroperating a user operation section (not shown) of the AV amplifier 300or operating a user operation section (not shown) of the televisionreceiver 200. Alternatively, the ON/OFF of the system audio mode in theAV amplifier 300 may be set by issuing speaker switching instruction byoperating the remote control (not shown) of the television receiver 200.

In the AV system 100 shown in FIG. 1, for example, when content playedback from a disc in the set top box 400 or a program selected by thetuner is viewed, by performing a switching operation from the televisionreceiver 200, an operation of a Play button of the set top box 400, andthe like, the following is executed.

That is, the image by the output video signal of the set top box 400 isdisplayed on a display panel (not shown) of the television receiver 200.In this case, the output video signal of the set top box 400 is suppliedto the television receiver 200 via the HDMI cable 703, the AV amplifier300, and the HDMI cable 701.

When the AV amplifier 300 is in a system audio mode of OFF, the sound bythe output audio signal of the set top box 400 is output from a speaker(not shown) of the television receiver 200. In this case, the outputaudio signal of the set top box 400 is supplied to the televisionreceiver 200 via the HDMI cable 703, the AV amplifier 300, and the HDMIcable 701.

When the AV amplifier 300 is in the system audio mode of ON, the soundby the output audio signal of the set top box 400 is output from thespeaker set provided to the AV amplifier 300. In this case, the outputaudio signal of the set top box 400 is supplied to the AV amplifier 300via the HDMI cable 703.

(Configuration of Television Receiver)

FIG. 3 is a block diagram showing a configuration example of thetelevision receiver (sink device) 200 that configures the AV system 100.The television receiver 200 includes HDMI terminals 201 and 202, an HDMIswitcher 204, an HDMI reception section 205, an antenna terminal 210,and a digital tuner 211. The television receiver 200 further includes ademultiplexer (Demux) 212, a moving picture expert group (MPEG) decoder213, a video/graphic processing circuit 214, a panel driving circuit215, and a display panel 216. The television receiver 200 furtherincludes a sound processing circuit 217, a sound amplification circuit218, and a speaker 219. The television receiver 200 further includes aninternal bus 230, a central processing unit (CPU) 231, a flash ROM 232,a DRAM 233, a reception section 234, a network I/F 235, a networkterminal 236, a microphone 237, and a camera 238.

The CPU 231 (control section) controls an operation of each section ofthe television receiver 200. The flash ROM 232 stores control softwareand data. The DRAM 233 configures, for example, a work area for the CPU231. The CPU 231 develops the software and data read from the flash ROM232 onto the DRAM 233, starts up the software, and controls each sectionof the television receiver 200. The CPU 231, the flash ROM 232, and theDRAM 233 are connected to the internal bus 230.

The reception section 234 receives, for example, an infrared remotecontrol signal (remote control code) transmitted from a remote controlRM and supplies the signal to the CPU 231. The user can operate thetelevision receiver 200 and another CEC-compatible device connected tothe television receiver 200 via the HDMI cable by operating the remotecontrol RM.

The network I/F 235 connects to a network via a network cable connectedto the network terminal 236, and transmits/receives data to/from each ofvarious types of devices connected to the network.

The antenna terminal 210 is a terminal that inputs a televisionbroadcast signal received by a reception antenna (not shown). Thedigital tuner 211 processes the television broadcast signal input to theantenna terminal 210, and outputs a given transport stream correspondingto a user-selected channel. The demultiplexer 212 extracts a partialtransport stream (TS) (a TS packet of video data and a TS packet ofaudio data) corresponding to the user-selected channel from thetransport stream obtained by the digital tuner 211.

The demultiplexer 212 extracts program specific information/serviceinformation (PSI/SI) from the transport stream obtained by the digitaltuner 211 and outputs the PSI/SI to the CPU 231. A plurality of channelsare multiplexed in the transport stream obtained by the digital tuner211. The process in which the demultiplexer 212 extracts the partial TSof any channel from the transport stream can be performed by obtaininginformation of a packet ID (PID) of any channel from the PSI/SI(PAT/PMT).

The MPEG decoder 213 performs a decoding process on a video packetizedelementary stream (PES) packet including the TS packet of the video dataobtained by the demultiplexer 212 to obtain video data. Also, the MPEGdecoder 213 performs a decoding process on an audio PES packet includingthe TS packet of the audio data obtained by the demultiplexer 212 toobtain audio data.

The video/graphic processing circuit 214 performs a scaling process, agraphics data superimposing process, and the like on the video dataacquired by the MPEG decoder 213, as necessary. Also, the video/graphicprocessing circuit 214 generates image data through a process based onan application stored in the flash ROM 232 in advance, and outputs theimage data to the panel driving circuit 215. The panel driving circuit215 drives the display panel 216 based on the video data output from thevideo/graphic processing circuit 214. The display panel 216 includes,for example, a liquid crystal display (LCD), an organicelectro-luminescence (EL), or a plasma display panel (PDP).

The sound processing circuit 217 performs a necessary process, such asD/A conversion, on the audio data obtained by the MPEG decoder 213. Thesound amplification circuit 218 amplifies an analog audio signal outputfrom the sound processing circuit 217 and supplies the resultant audiosignal to the speaker 219. The sound processing circuit 217 converts theaudio data obtained by the MPEG decoder 213 into a digital opticalsignal and outputs the digital optical signal to the optical outputterminal 203.

The HDMI switcher 204 selectively connects the HDMI terminals 201 and202 to the HDMI reception section 205. The HDMI reception section 205 isselectively connected to any of the HDMI terminals 201 and 202 via theHDMI switcher 204. This HDMI reception section 205 receives video andaudio data transmitted from an external device (a source device or arepeater device) connected to the HDMI terminal 201 or 202 throughcommunication conforming to HDMI. This HDMI reception section 205 willbe described in detail later.

(Operation of Television Receiver)

Here, an operation of the television receiver 200 shown in FIG. 3 willbe briefly described. The television broadcast signal input to theantenna terminal 210 is supplied to the digital tuner 211. This digitaltuner 211 processes the television broadcast signal to obtain atransport stream corresponding to the user-selected channel. Thistransport stream is supplied to the demultiplexer 212. The demultiplexer212 extracts a partial TS (a TS packet of video data and a TS packet ofaudio data) corresponding to the user-selected channel from thetransport stream. This partial TS is supplied to the MPEG decoder 213.

The MPEG decoder 213 performs a decoding process on a video PES packetincluding the TS packet of the video data to obtain video data. Thevideo/graphic processing circuit 214 performs a scaling process, agraphics data superimposing process and the like on the video data, asnecessary, and supplies the resultant video data to the panel drivingcircuit 215. Accordingly, an image corresponding to the user-selectedchannel is displayed on the display panel 216.

The MPEG decoder 213 performs a decoding process on an audio PES packetincluding the TS packet of the audio data to obtain audio data. Thesound processing circuit 217 performs a necessary process such as D/Aconversion on the audio data, and the sound amplification circuit 218amplifies the audio data and supplies the audio data to the speaker 219.Accordingly, an audio corresponding to the user-selected channel isoutput from the speaker 219.

The audio data obtained by the MPEG decoder 213 is converted into, forexample, a digital optical signal conforming to the S/PDIF standard bythe sound processing circuit 217, and output to the optical outputterminal 203. Accordingly, the television receiver 200 can transmit theaudio data to the external device via the optical cable. In the AVsystem 100 shown in FIG. 1, as described above, the audio data from thetelevision receiver 200 is supplied to the AV amplifier 300 via theoptical cable 702.

When the AV amplifier 300 is in a system audio mode of ON, an audio bythe audio data from the television receiver 200 is output from thespeaker set provided to the AV amplifier 300. In this case, the soundamplification circuit 218 enters a mute ON state under control of theCPU 231, and the audio is not output from the speaker 219 of thetelevision receiver 200.

In the HDMI reception section 205, video and audio data input to theHDMI terminal 201 or 202 via the HDMI cable is obtained. The video datais supplied to the video/graphic processing circuit 214. The audio datais supplied to the sound processing circuit 217. A subsequent operationis the same as that upon reception of the above-described televisionbroadcast signal, the image is displayed on the display panel 216, andthe audio is output from the speaker 219.

In the AV system 100 shown in FIG. 1, for example, when an image and anaudio by video data and audio data from the set top box 400 are watchedand listened to, the state becomes a state in which an image and anaudio by the video data and the audio data acquired by the HDMIreception section 205, as described above, are watched and listened to.

Even in this case, when the AV amplifier 300 is in a system audio modeof ON, the audio by the audio data is output from the speaker setprovided to the AV amplifier 300, and the sound amplification circuit218 of the television receiver 200 enters a mute ON state, such that theaudio is not output from the television receiver 200.

(Configuration of AV Amplifier)

FIG. 4 is a block diagram showing a configuration example of the AVamplifier 300 that configures the AV system 100. The AV amplifier 300includes HDMI terminals 301 to 304, an optical input terminal 305, anHDMI switcher 306, an HDMI reception section 307, an HDMI transmissionsection 308, and a conversion section 310. Further, the AV amplifier 300includes an analog audio input terminal 311, an A/D converter 315, aselector 316, and a digital signal processor (DSP) 317. Still further,the AV amplifier 300 includes a sound amplification circuit 318, aninternal bus 320, a CPU 321, ROM 322, and RAM 323.

The CPU 321 (control section) controls operation of each section of theAV amplifier 300. The ROM 322 stores control software and data. The RAM323 configures, for example, a work area of the CPU 321. The CPU 321develops the software or data read from the ROM 322 onto the RAM 323 tostart up the software and control each section of the AV amplifier 300.The CPU 321, the ROM 322, and the RAM 323 are connected to the internalbus 320. The CPU 321, the ROM 322, and the RAM 323 may be amicrocomputer of one chip (one chip microcomputer).

An operation section 324 and a display section 325 are connected to theCPU 321. The operation section 324 and the display section 325 configurea user interface. Using the operation section 324, the user can performselection of an output audio of the AV amplifier 300, an operationsetting, and the like. The user can set the system audio mode to ON/OFFusing the operation section 324. Further, the CPU 321 cantransmit/receive a CEC signal to/from an external device connected tothe HDMI terminals 301 to 304. For example, the CEC signal may betransmitted/received via a CEC line, which will be described later. TheCEC signal may function as the above-mentioned control signal.

This operation section 324 includes keys, buttons, a dial, a remotecontrol signal transmission/reception section, and the like disposed ona casing, which is not shown, of the AV amplifier 300. The displaysection 325 displays an operation status of the AV amplifier 300, a useroperation state, and the like, and includes a fluorescent display tube,a liquid crystal display (LCD), or the like.

The optical input terminal 305 is a terminal that inputs a digitaloptical signal via the optical cable. An optical output terminal 312 isa terminal that outputs a digital optical signal via the optical cable.

The conversion section 310 generates a clock LRCK having the samefrequency (e.g., 48 kHz) as a sampling frequency of an audio signal, amaster clock MCK that is, for example, 512 or 256 times the samplingfrequency, left and right 24-bit audio data LDATA and RDATA occurringevery period of the clock LRCK, and a bit clock BCK synchronized witheach bit of the data, from the digital optical signal input to theoptical input terminal 305, and supplies them to the selector 316.

Further, the conversion section 310 transmits, from the optical outputterminal 312, the digital optical signal input to the optical inputterminal 305. Further, the conversion section 310 can supply an audioreturn channel (ARC) signal out of the signals transmitted from anexternal device connected to the HDMI terminal 304 to the selector 316.The description on the ARC signal will be made in detail later, andaudio data can be received using the ARC signal. The ARC signal may betransmitted/received using a reserved line which will be describedlater, for example.

The analog audio input terminal 311 is a terminal that inputs left andright analog audio signals obtained in the external device. The A/Dconverter 315 converts the analog audio signal input by the analog audioinput terminal 311 into digital audio data and supplies the digitalaudio data to the selector 316.

The HDMI switcher 306 selectively connects the HDMI terminals 301 to 303to the HDMI reception section 307. The HDMI reception section 307 isselectively connected to any of the HDMI terminals 301 to 303 via theHDMI switcher 306. This HDMI reception section 307 receives video andaudio data transmitted in one direction from external devices (sourcedevices) connected to the HDMI terminals 301 to 303 throughcommunication conforming to HDMI.

The HDMI reception section 307 supplies the audio data to the selector316, and supplies the video and audio data to the HDMI transmissionsection 308. The HDMI transmission section 308 transmits, from the HDMIterminal 304, the baseband video and audio data supplied from the HDMIreception section 307 through the communication conforming to HDMI.Thus, the AV amplifier 300 has a repeater function. The HDMI receptionsection 307 and the HDMI transmission section 308 will be described indetail later.

The selector 316 selectively extracts the audio data supplied from theHDMI reception section 307, the audio data supplied from the conversionsection 310, or the audio data supplied from the A/D converter 315, andsupplies the audio data to the DSP 317.

The DSP 317 processes the audio data obtained by the selector 316, andperforms an equalization process for adjusting a volume for eachfrequency band, a sound image localization process for setting alocalization position of a sound image, and the like.

The sound amplification circuit 318 converts the audio data output fromthe DSP 317 into an analog signal, and outputs the analog signal to thespeaker set 350. Further, the sound amplification circuit 318 outputsvarious types of signals for controlling the speaker set 350, which areoutput from the CPU 321, to the speaker set 350. Further, when receivingthe analog signal from the speaker set 350, the sound amplificationcircuit 318 converts the received analog signal into a digital signal,and outputs the digital signal obtained by the conversion to the CPU321.

(Operation of AV Amplifier)

Here, an operation of the AV amplifier 300 shown in FIG. 4 will bebriefly described. In the HDMI reception section 307, the baseband videoand audio data input to the HDMI terminals 301 to 303 via the HDMI cableis obtained. This video and audio data is supplied to the HDMItransmission section 308 and transmitted to the HDMI cable connected tothe HDMI terminal 304.

Further, the audio data obtained in the HDMI reception section 307 issupplied to the selector 316. In the selector 316, the audio datasupplied from the HDMI reception section 307, the audio data suppliedfrom the conversion section 310, or the audio data supplied from the A/Dconverter 315 is selectively extracted and supplied to the DSP 317.

In the DSP 317, a necessary process is performed on the audio data, suchas an equalization process for adjusting a volume for each frequencyband or a sound image localization process for setting a localizationposition of a sound image. The audio signal of each channel output fromthe DSP 317 is output by the speaker set 350.

For example, in the AV system 100 shown in FIG. 1, when the programtuned by the digital tuner 211 of the television receiver 200 is viewedand the AV amplifier 300 is in a system audio mode of ON, the followingoperation is performed. That is, the selector 316 extracts the audiodata from the conversion section 310. Accordingly, the audio signals ofthe respective channels according to the audio data of the program tunedby the digital tuner 211 of the television receiver 200 are output tothe sound amplification circuit 318. Thus, the audio of the programtuned by the digital tuner 211 of the television receiver 200 is outputfrom the speaker set 350.

When the program tuned by the digital tuner 211 of the televisionreceiver 200 is viewed and the AV amplifier 300 is in the system audiomode of OFF, the sound amplification circuit 318 enters a mute ON state.Accordingly, the audio signal is not supplied from the soundamplification circuit 318 to the speaker set 350. Note that, when thesound amplification circuit 318 is in the mute ON state, in addition tothat the sound amplification circuit 318 is in the mute ON state, theDSP 317 may also enter a mute ON state. In addition, a component otherthan the DSP 317 and the sound amplification circuit 318 may be in themute ON state. The same applies hereinafter.

For example, in the AV system 100 shown in FIG. 1, when an image and anaudio by the video data and the audio data from the set top box 400 arewatched and listened to and the AV amplifier 300 is in the system audiomode of ON, the following operation is performed. That is, the HDMIterminal 301 is connected to the HDMI reception section 307 via the HDMIswitcher 306. Further, in the selector 316, the audio data from the HDMIreception section 307 is extracted. Accordingly, the audio signals ofthe respective channels according to the audio data from the set top box400 are output to the sound amplification circuit 318. Thus, the audioby the audio data from the set top box 400 is output from the speakerset 350.

Note that, when the image and the audio by the video data and the audiodata from the set top box 400 are to be watched and listened to and theAV amplifier 300 is in the system audio mode of OFF, the soundamplification circuit 318 enters a mute ON state, and the audio signalis not supplied from the sound amplification circuit 318 to the speakerset 350.

(Configuration of Set Top Box)

FIG. 5 is a block diagram showing a configuration example of the set topbox (source device) 400. The set top box 400 includes an HDMI terminal401, an optical output terminal 403, an antenna terminal 410, and adigital tuner 411. Further, the set top box 400 includes a demultiplexer(Demux) 412, a moving picture expert group (MPEG) decoder 413, avideo/graphic processing circuit 414, and an HDMI transmission section415. The set top box 400 further includes a sound processing circuit417, a sound amplification circuit 418, and an analog sound outputterminal 419. Still further, the set top box 400 includes an internalbus 430, a central processing unit (CPU) 431, flash ROM 432, DRAM 433, areception section 434, a network I/F 435, and a network terminal 436.

The CPU 431 controls an operation of each section of the set top box400. The flash ROM 432 stores control software and data. The DRAM 433configures, for example, a work area for the CPU 431. The CPU 431develops the software and data read from the flash ROM 432 onto the DRAM433, starts up the software, and controls each section of the set topbox 400. The CPU 431, the flash ROM 432, and the DRAM 433 are connectedto the internal bus 430.

The reception section 434 receives, for example, an infrared remotecontrol signal (remote control code) transmitted from a remote controlRM and supplies the signal to the CPU 431. The user can operate the settop box 400 and another CEC-compatible device connected to the set topbox 400 via the HDMI cable by operating the remote control RM.

The network I/F 435 connects to a network via a network cable connectedto the network terminal 436, and transmits/receives data to/from each ofvarious types of devices connected to the network.

The antenna terminal 410 is a terminal that inputs a televisionbroadcast signal received by a reception antenna (not shown). Thedigital tuner 411 processes the television broadcast signal input to theantenna terminal 410, and outputs a given transport stream correspondingto a user-selected channel. The demultiplexer 412 extracts a partialtransport stream (TS) (a TS packet of video data and a TS packet ofaudio data) corresponding to the user-selected channel from thetransport stream obtained by the digital tuner 411.

The demultiplexer 412 extracts program specific information/serviceinformation (PSI/SI) from the transport stream obtained by the digitaltuner 411 and outputs the PSI/SI to the CPU 431. A plurality of channelsare multiplexed in the transport stream obtained by the digital tuner411. The process in which the demultiplexer 412 extracts the partial TSof any channel from the transport stream can be performed by obtaininginformation of a packet ID (PID) of any channel from the PSI/SI(PAT/PMT).

The MPEG decoder 413 performs a decoding process on a video packetizedelementary stream (PES) packet including the TS packet of the video dataobtained by the demultiplexer 412 to obtain video data. Also, the MPEGdecoder 413 performs a decoding process on an audio PES packet includingthe TS packet of the audio data obtained by the demultiplexer 412 toobtain audio data.

The video/graphic processing circuit 414 performs a scaling process, agraphics data superimposing process, and the like on the video dataacquired by the MPEG decoder 413, as necessary. Also, the video/graphicprocessing circuit 414 generates image data through a process based onan application stored in the flash ROM 432 in advance, and outputs theimage data to the HDMI transmission section 415. The HDMI transmissionsection 415 outputs the video data from the video/graphic processingcircuit 414 to the AV amplifier 300 through the HDMI terminal 401.

The sound processing circuit 417 performs a necessary process, such asD/A conversion, on the audio data obtained by the MPEG decoder 413. Thesound amplification circuit 418 amplifies an analog audio signal outputfrom the sound processing circuit 417 and supplies the AV amplifier 300with the amplified analog audio signal through the analog sound outputterminal 419.

(Operation of Set Top Box)

Here, an operation of the set top box 400 shown in FIG. 5 will bebriefly described. The television broadcast signal input to the antennaterminal 410 is supplied to the digital tuner 411. This digital tuner411 processes the television broadcast signal to obtain a transportstream corresponding to the user-selected channel. This transport streamis supplied to the demultiplexer 412. The demultiplexer 412 extracts apartial TS (a TS packet of video data and a TS packet of audio data)corresponding to the user-selected channel from the transport stream.This partial TS is supplied to the MPEG decoder 413.

The MPEG decoder 413 performs a decoding process on a video PES packetincluding the TS packet of the video data to obtain video data. Thevideo/graphic processing circuit 414 performs a scaling process, agraphics data superimposing process and the like on the video data, asnecessary, and supplies the resultant video data to the HDMItransmission section 415. The video data is then output to the AVamplifier 300 from the HDMI transmission section 415 through the HDMIterminal 401. Accordingly, a video corresponding to the user-selectedchannel is output from the HDMI terminal 401.

The MPEG decoder 413 performs a decoding process on an audio PES packetincluding the TS packet of the audio data to obtain audio data. Thesound processing circuit 417 performs a necessary process such as D/Aconversion on the audio data, and the sound amplification circuit 418amplifies the audio data and supplies the audio data to the analog soundoutput terminal 419. Accordingly, an audio corresponding to theuser-selected channel is output from the analog sound output terminal419.

The audio data obtained by the MPEG decoder 413 is converted into, forexample, a digital optical signal conforming to the S/PDIF standard bythe sound processing circuit 417, and output to the optical outputterminal 403. Accordingly, the set top box 400 can transmit the audiodata to the external device via the optical cable.

(Detail of HDMI Communication)

FIG. 6 is a block diagram showing a configuration example of an HDMItransmission section (HDMI transmission section 308) and an HDMIreception section (HDMI reception section 307).

The HDMI transmission section (HDMI source) performs transmission in oneunit in a valid image period (hereinafter, referred to as an activevideo period as appropriate) that is a period obtained by excluding ahorizontal blacking period and a vertical blacking period from a periodfrom one vertical synchronization signal to a next verticalsynchronization signal. That is, in the active video period, the HDMItransmission section transmits, in one direction, a differential signalcorresponding to non-compressed image pixel data corresponding to onescreen to the HDMI reception section (HDMI sink) via a plurality ofchannels. In the horizontal blacking period or the vertical blackingperiod, the HDMI transmission section transmits, in one direction, adifferential signal corresponding to at least the audio data associatedwith the image, control data, other auxiliary data, and the like to theHDMI reception section via a plurality of channels.

The HDMI transmission section includes a transmitter 81. The transmitter81 converts, for example, non-compressed image pixel data into acorresponding differential signal, and serially transmits, in onedirection, the differential signal to the HDMI reception sectionconnected via the HDMI cable, via a plurality of channels, i.e., threeTMDS channels #0, #1, and #2.

The transmitter 81 converts audio data associated with non-compressedimage, necessary control data, other auxiliary data, and the like into acorresponding differential signal. The transmitter 81 seriallytransmits, in one direction, the differential signal to the HDMIreception section connected via the HDMI cable, via three TMDS channels#0, #1, and #2.

The transmitter 81 transmits the pixel clock synchronized to the pixeldata transmitted via three TMDS channels #0, #1, and #2 to the HDMIreception section connected via the HDMI cable via the TMDS clockchannel. Here, via one TMDS channel #i (i=0, 1, 2), 10-bit pixel data istransmitted during one clock of the pixel clock.

The HDMI reception section, in an active video period, receives adifferential signal corresponding to the pixel data that is transmittedin one direction from the HDMI transmission section via a plurality ofchannels. Further, the HDMI reception section, in the horizontalblacking period or the vertical blacking period, receives a differentialsignal corresponding to audio data or control data that is transmittedin one direction from the HDMI transmission section via a plurality ofchannels.

That is, the HDMI reception section includes a receiver 82. The receiver82 receives a differential signal corresponding to the pixel data and adifferential signal corresponding to the audio data or the control datatransmitted in one direction from the HDMI transmission section via theTMDS channels #0, #1, and #2. In this case, the receiver 82 receives insynchronization with the pixel clock transmitted from the HDMItransmission section via the TMDS clock channel.

The transmission channels of the HDMI system include three TMDS channels#0 to #2 as transmission channels for serially transmitting pixel dataand audio data, and a TMDS clock channel as a transmission channel thattransmits a pixel clock. Further, there is a transmission channel calleda display data channel (DDC) 83 or a CEC line 84.

The DDC 83 is used for the HDMI transmission section to read enhancedextended display identification data (E-EDID) from the HDMI receptionsection connected via the HDMI cable. The DDC 83 includes two signallines, not shown, included in the HDMI cable.

That is, the HDMI reception section includes an EDID ROM 85, in additionto the HDMI receiver 82. The EDID ROM 85 stores an E-EDID that isperformance information about its performance(configuration/capability). The HDMI transmission section reads, fromthe HDMI reception section connected via the HDMI cable, the E-EDID ofthe HDMI reception section via the DDC 83. Based on the read E-EDID, theHDMI transmission section recognizes, for example, a format (profile) ofan image to which an electronic device having the HDMI reception sectioncorresponds, such as RGB, YCbCr4:4:4, YCbCr4:2:2, and the like.

The CEC line 84 includes one signal line, which is not shown, includedin the HDMI cable, and is used to perform bidirectional communication ofcontrol data between the HDMI transmission section and the HDMIreception section. The bidirectional communication is performed in timedivision.

A line 86 connected to a pin called a hot plug detect (HPD) is includedin the HDMI cable. A source device can detect a connection of a sinkdevice using the line 86. Further, the HDMI cable includes a line 87used to supply power from the source device to the sink device. Inaddition, the HDMI cable also includes a reserved line 88.

FIG. 7 is a diagram showing a block configuration of data transmittedthrough a CEC line (CEC channel). In data transmission initiation, astart bit is arranged, a header block is arranged, and then any number(n) of data blocks including data to be actually transmitted arearranged.

FIG. 8 is a diagram showing an example of data structure of a headerblock. A logical address (source address) of a transmission source and alogical address (sink address) of a transmission destination arearranged in the header block. The logical address of a transmissionsource corresponds to an initiator, and the logical address of atransmission destination corresponds to a destination.

The CEC message has a structure in which a maximum of sixteen pieces of10-bit data are connected. Among the 10 bits, last 2 bits include an EOMbit indicating that it is a last bit, and an ACK bit indicating that themessage is recognized, as shown in FIG. 8. Accordingly, hereinafter,first 8 bits of the 10-bit data are treated as one byte.

A first one byte of the CEC command includes 4 bits in which a logicaladdress of a command transmission source is stored, and 4 bits in whicha logical address of a command transmission destination is stored. Asshown in FIG. 2, the television receiver 200, generally, has a logicaladdress designated as 0 and the AV amplifier 300 has a logical addressdesignated as 5. Further, command transmission methods include broadcastby which transmission is performed from one device to all devices, andunicast by which transmission is performed from one device to a devicehaving a specific logical address.

Heretofore, there has been described the configuration example of the AVsystem 100 that may be applied an embodiment of the present disclosure.

<2-2. Configuration Example of Communication System>

Subsequently, an overall configuration of a communication systemaccording to an embodiment of the present disclosure will be described.FIG. 9 is a diagram showing an overall configuration example of acommunication system according to an embodiment of the presentdisclosure. As shown in FIG. 9, the communication system according to anembodiment of the present disclosure is configured such that an AVsystem 100-1 and an AV system 100-2 are communicable with each otherthrough a network. In more detail, the communication system according toan embodiment of the present disclosure is configured such that atelevision receiver 200 (audio device) in the AV system 100-1 and atelevision receiver 200 (communication partner device) in the AV system100-2 are communicable with each other through a network. In thefollowing description, let us assume that the AV system 100-1 is used bya user himself/herself and the AV system 100-2 is used by a partner whomthe user is having a conversation with.

FIG. 10 is a diagram showing a layout example of a screen displayed onthe display panel 216 by the television receiver 200 in the AV system100 according to an embodiment of the present disclosure. Referring toFIG. 10, the display panel 216 of the television receiver 200 displays aTV screen R0, a partner display screen R1, an own display screen R2, andan SNS screen R3. The TV screen R0 may display a video corresponding toa broadcast signal input from the antenna terminal 210, or may display avideo corresponding to a broadcast signal input from the set top box 400through the AV amplifier 300 (audio device). Note that the displaying ofthe screen as shown in FIG. 10 may be triggered by a button-pressingoperation performed by the user.

For example, the user himself/herself who is viewing the screendisplayed by the television receiver 200 of the AV system 100-1 is shotby the camera 238 included in the television receiver 200. The videoshot by the camera 238 is displayed as the own display screen R2, and isalso transmitted to the television receiver 200 of the AV system 100-2that the partner uses through the network terminal 236. Further, a videoof the partner transmitted from the AV system 100-2 that the partneruses is displayed as the partner display screen R1. In the same manner,the television receiver 200 of the AV system 100-2 may also display thescreen as shown in FIG. 10.

Further, the user can have a conversation with the partner while viewingthe TV screen R0 (or, the partner display screen R1, the own displayscreen R2, or the SNS screen R3). To be specific, a sound that thepartner uttered (hereinafter, also referred to as “telephoniccommunication destination sound”) is detected by the microphone 237included in the television receiver 200 of the AV system 100-2 that thepartner uses, and is transmitted by the network I/F 235 through thenetwork terminal 236. The television receiver 200 of the AV system 100-1receives the telephonic communication destination sound by the networkI/F 235 through the network terminal 236.

In the television receiver 200 of the AV system 100-1, the soundprocessing circuit 217 adds, in accordance with the control performed bythe CPU 231, the telephonic communication destination sound to audio(hereinafter, also referred to as “TV sound”) extracted from thebroadcast signal, and outputs the telephonic communication destinationsound-added TV sound from the speaker 219 through the soundamplification circuit 218. The user using the AV system 100-1 can uttera sound while listening to the telephonic communication destinationsound and the TV sound. The sound uttered by the user is detected by themicrophone 237, and is transmitted to the television receiver 200 of theAV system 100-2 by the network I/F 235 through the network terminal 236.

However, the telephonic communication destination sound and the TV soundoutput from the speaker 219 may also propagate and detected by themicrophone 237. As a result, the telephonic communication destinationsound and the TV sound go and come back between the AV system 100-1 andAV system 100-2 while being attenuated and causing a delay time, whichmay cause a phenomenon that the sound to which an echo is added may beoutput from the television receiver 200 and it becomes difficult tocarry out a conversation comfortably with the partner. Accordingly, thepresent description mainly suggests technology capable of making aconversation carried out with the partner while listening to the TVsound more comfortable.

To be specific, in accordance with the control performed by the CPU 231,the sound processing circuit 217 performs processing (hereinafter, “echocancellation processing”) of eliminating a given sound signal(hereinafter, also referred to as “echo”) from a microphone detectionsignal which is the audio signal that is propagated and detected by themicrophone 237, and generates an elimination signal (hereinafter, alsoreferred to as “echo-eliminated signal”) obtained by eliminating thegiven sound signal. The CPU 231 causes the television receiver 200 ofthe AV system 100-2 to output the generated echo-eliminated signal.

Through such processing, the possibility that the sound to which an echois added is output is reduced, and the conversation carried out with thepartner while listening to the TV sound can be made more comfortable.The audio signal including the TV sound and the telephonic communicationdestination sound may be output from the speaker 219 of the televisionreceiver 200, and may also be output from the speaker set 350 of the AVamplifier 300. First, the case where the audio signal including the TVsound and the telephonic communication destination sound is output fromthe speaker 219 of the television receiver 200 (hereinafter, also simplyreferred to as “case of a single TV”) will be described.

FIG. 11 is a diagram showing a flow of a sound in a case of a single TV.As shown in FIG. 11, the CPU 231 may output the audio signal includingthe TV sound and the telephonic communication destination sound from thespeaker 219 of the television receiver 200. In such a case, as shown inFIG. 11, the TV sound and the telephonic communication destination soundthat are output may propagate and may be detected by the microphone 237together with the sound uttered by the user. Accordingly, the soundprocessing circuit 217 performs the echo cancellation processing andgenerates the echo-eliminated signal, and the CPU 231 may cause thetelevision receiver 200 of the AV system 100-2 to output theecho-eliminated signal. Hereinafter, description will be continued onthe echo cancellation processing.

FIG. 12 is a diagram illustrating a configuration related to echocancellation processing in a case of the single TV. As shown in FIG. 12,the television receiver 200 includes, as for the configuration relatedto the echo cancellation processing, the speaker 219, an A/D conversionsection 217 a, an adaptive filter 217 b, a D/A conversion section 217 c,and the microphone 237. Further, the variables shown in FIG. 12 andequations are described as follows.

-   -   r[n]: audio signal (digital signal)    -   x[n]: microphone detection signal (digital signal)    -   z[n]: echo estimation signal    -   y[n]: echo-eliminated signal    -   h[n]: adaptive filter coefficient    -   r(t): audio signal (analog signal)    -   x(t): microphone detection signal (analog signal)

h[n] = (h[0], h[1], …  , h[N − 1])${z\lbrack n\rbrack} = {\sum\limits_{i = 0}^{N - 1}{{r\lbrack {n - i} \rbrack} \cdot {h\lbrack i\rbrack}}}$y[n] = x[n] − z[n]${h\lbrack n\rbrack} = {\underset{h}{\arg \; \min}{E\lbrack {{{x\lbrack n\rbrack} - {\sum\limits_{i = 0}^{N - 1}{{r\lbrack {n - i} \rbrack} \cdot {h\lbrack i\rbrack}}}}}^{2} \rbrack}}$

The microphone detection signal obtained by detection by the microphone237 is converted into a digital signal in the A/D conversion section 217a and is output to an adder. On the other hand, the audio signalincluding the TV sound and the telephonic communication destinationsound is output to the adaptive filter 217 b, and is also converted intoan analog signal in the D/A conversion section 217 c and is output fromthe speaker 219. The audio signal output to the adaptive filter 217 bcauses a delay time D_(TV). The reason for causing the delay time D_(TV)is that a delay occurs for the audio signal to leave the speaker 219 andto enter the microphone 237. Note that the delay time D_(TV) is roughlyclassified into a system delay that occurs inside the system and apropagation delay that occurs outside the system.

In the adaptive filter 217 b, an echo estimation signal (given soundsignal) is calculated and is output to the adder. The adaptive filtercoefficient used for the calculation performed by the adaptive filter217 b may be learned by a given adaptive signal processing algorithm.The type of the adaptive signal processing algorithm is not particularlylimited, and may be a least mean square (LMS) method and a learningidentification method. In the adder, the echo estimation signal issubtracted from the microphone detection signal to thereby calculate theecho-eliminated signal.

Here, an example of calculation of the adaptive filter coefficient willbe described. FIG. 13 is a diagram showing an example of an adaptivefilter coefficient obtained by learning. Referring to FIG. 13, in theadaptive filter coefficient, there is a zero signal section before asignificant waveform. The reason for the zero signal section beingpresent is that a delay occurs for the played back audio signal to leavethe speaker to enter the microphone.

If an adaptive filter of an infinite length can be used, the adaptivefilter can be applied to any delay. However, as shown in FIG. 13, sincethe length of the adaptive filter is actually finite, it is desirablethat the fixed delay part be achieved by a delay buffer and be excludedfrom the target of the calculation of the adaptive filter coefficientfrom the viewpoint of calculation cost. For the fixed delay part, avalue less than the value of the sum of the system delay and thepropagation delay may be used.

Subsequently, a flow of an operation of the echo cancellation processingin the case of the single TV will be described. FIG. 14 is a flowchartshowing a flow of an operation of the echo cancellation processing inthe case of the single TV. First, in the television receiver 200, theCPU 231 sets the system delay (set system delay D to delay time D_(TV))(Step S101), and initializes a filter coefficient (Step S102).Subsequently, the CPU 231 starts the echo cancellation (Step S103).

When the echo cancellation starts, the adaptive filter 217 b acquiresthe microphone detection signal obtained by detection by the microphone237 (Step S104), and also acquires the audio signal including the TVsound and the telephonic communication destination sound (Step S105).Subsequently, the adaptive filter 217 b performs echo estimation(generates an echo estimation signal) (Step S106), and the addereliminates the echo estimation signal from the microphone detectionsignal to thereby generate the echo-eliminated signal, and outputs thegenerated echo-eliminated signal (Step S107). Further, the CPU 231updates the filter coefficient (Step S108), and, in the case where thetelephonic communication is not terminated, the processing returns toStep S104, and in the case where the telephonic communication isterminated, the echo cancellation ends (Step S109).

Heretofore, the case of a single TV has been described. In order toenhance the sound quality of the sound output from the televisionreceiver 200, there is a case where the AV amplifier 300 connected tothe television receiver 200 is used for the sound output. That is, thereis also the case where the audio signal including the TV sound and thetelephonic communication destination sound is output from the speakerset 350 of the AV amplifier 300 connected to the television receiver 200(hereinafter, simply referred to as “case of an external amplifier”).Hereinafter, the case of the external amplifier will be described.

Here, in the case where the set top box 400 and the AV amplifier 300establish HDMI connections to the television receiver 200, since theaudio signal received from the AV amplifier 300 is generally richer thanthe audio signal received from the television receiver 200, theconnection may be established in the order of the set top box 400, theAV amplifier 300, and the television receiver 200. For example, in thecase where the connection is performed in the order of the set top box400, the television receiver 200, and the AV amplifier 300, it generallybecomes difficult to playback a multichannel signal in the AV amplifier300.

In the case of a general HDMI repeater function of the AV amplifier 300,when the AV amplifier 300 outputs a sound, EDID is controlled such thatthe audio signal-receiving performance as the AV amplifier 300 is shown,and a signal from the set top box 400 is input to the AV amplifier 300via the repeater of the AV amplifier 300. In this case, while a sound isoutput from the speaker set 350 of the AV amplifier 300, only the videosignal is generally transmitted to the television receiver 200.

While connection is established in this way, since the audio signal isnot transmitted to the television receiver 200, even if the televisionreceiver 200 has a function of performing the echo cancellation, it isdifficult for the television receiver 200 to receive the audio signalvia the HDMI, and it is difficult for the television receiver 200 toperform the echo cancellation.

The following may be performed for causing the television receiver 200to execute the echo cancellation on the sound input from the set top box400 or the like via an HDMI terminal of the AV amplifier 300. That is,the HDMI signal received from the set top box 400 in the AV amplifier300 is passed as it is to the television receiver 200, the echocancellation is performed in the television receiver 200, the sound fromthe television receiver 200 is returned to the AV amplifier 300, and thesound may be played back.

FIG. 15 is a diagram showing a flow of video data and audio data atnormal times in a case of an external amplifier. As shown in FIG. 15,let us assume that input data is input from the set top box 400 throughthe HDMI terminal 301 to the AV amplifier 300, for example. The inputdata includes video data and audio data. The CPU 321 can separate theaudio data from the input data that is input from the set top box 400through the HDMI terminal 301 and can output the audio data from thespeaker set 350. The user can listen to the audio output from thespeaker set 350 in this way.

Further, the CPU 321 can separate the video data from the input datathat is input from the set top box 400 through the HDMI terminal 301 andcan cause the television receiver 200 to output the video data. Thevideo data is output to the television receiver 200 through the HDMIterminal 304 in accordance with the control performed by the CPU 321.Further, the video data input to the television receiver 200 via theHDMI terminal 201 is output as a video from the display panel 216 of thetelevision receiver 200 in accordance with control performed by the CPU231. The user can view the video output from the television receiver 200in this manner.

Next, let us assume a case where the cancellation is performed in thecase of the external amplifier. In such a case, it becomes necessary toprovide the AV amplifier 300 with a dedicated circuit including amicrophone, and the use thereof is limited, which is impracticable. Ifthe AV amplifier 300 is not provided with the dedicated circuitincluding the microphone and is connected to the television receiver200, the cancellation which has been performed in the case of a singleTV is not performed any more. This does not match the action of the userof connecting the AV amplifier 300 to the television receiver 200 forthe sake of enhancing the sound quality.

Accordingly, it is better to detect the audio signal including the TVsound and the telephonic communication destination sound output from theAV amplifier 300 by the microphone 237 mounted on the televisionreceiver 200, and to perform the cancellation in the television receiver200. FIG. 16 is a diagram showing a flow of video data and audio data ata time of cancellation interlocking state in the case of the externalamplifier. As shown in FIG. 16, for example, let us assume that inputdata is input from the set top box 400 through the HDMI terminal 301 tothe AV amplifier 300. The input data includes video data and audio data.The CPU 321 can output the input data input from the set top box 400through the HDMI terminal 301 to the television receiver 200 through theHDMI terminal 304.

Further, the CPU 231 can separate the video data from the input datainput from the AV amplifier 300 through the HDMI terminal 201. The videodata is output as a video from the display panel 216 of the televisionreceiver 200 in accordance with control performed by the CPU 231. Theuser can view the video output from the television receiver 200 in thismanner. Further, the CPU 231 adds the telephonic communicationdestination sound received by the network I/F 235 through the networkterminal 236 to the audio data (TV sound), and outputs the audio dataincluding the TV sound and the telephonic communication destinationsound to the AV amplifier 300 through the optical output terminal 203.

The AV amplifier 300 is capable of outputting the audio data inputthrough the optical input terminal 305, the ARC-compatible HDMI terminal304, or the analog audio input terminal 311 to the speaker set 350. Theuser can listen to the TV sound and the telephonic communicationdestination sound output from the speaker set 350 in this manner. Theaudio data including the TV sound and the telephonic communicationdestination sound is detected as a microphone detection signal togetherwith the sound (hereinafter, also referred to as “telephoniccommunication source sound”) uttered by the user himself/herself.However, with the echo cancellation performed by the sound processingcircuit 217, an echo-eliminated signal which is obtained by eliminatingan echo estimation signal from the microphone detection signal isgenerated.

The echo-eliminated signal mainly includes the telephonic communicationsource sound. The network I/F 235 can transmit the echo-eliminatedsignal generated by the sound processing circuit 217 to thecommunication partner device through the network terminal 236.Hereinafter, description will be continued on the echo cancellationprocessing.

FIG. 17 is a diagram illustrating a configuration related to echocancellation processing in the case of the external amplifier. As shownin FIG. 17, the television receiver 200 includes, as for theconfiguration related to the echo cancellation processing, an A/Dconversion section 217 a, an adaptive filter 217 b, and the microphone237. Further, the AV amplifier 300 connected to the television receiver200 includes, as for the configuration related to the echo cancellationprocessing, a DSP 317, a D/A conversion section 318 a, the speaker set350, and the CPU 321.

The microphone detection signal obtained by detection by the microphone237 is converted into a digital signal in the A/D conversion section 217a and is output to an adder. On the other hand, the audio signalincluding the TV sound and the telephonic communication destinationsound is output to the adaptive filter 217 b, subjected to soundprocessing by the DSP 317 of the AV amplifier 300, converted into ananalog signal in the D/A conversion section 318 a, and is output fromthe speaker set 350. The audio signal output to the adaptive filter 217b causes a delay time D_(TV)+D_(amp). The reason for causing the delaytime D_(TV)+D_(amp) is that a delay occurs for the audio signal to leavethe speaker set 350 and to enter the microphone 237. Note that the delaytime D_(TV)+D_(amp) is roughly classified into a system delay thatoccurs inside the system and a propagation delay that occurs outside thesystem.

In the adaptive filter 217 b, an echo estimation signal is calculatedand is output to the adder. The adaptive filter coefficient used for thecalculation performed by the adaptive filter 217 b may be learned by agiven adaptive signal processing algorithm. The type of the adaptivesignal processing algorithm is not particularly limited, and may be aleast mean square (LMS) method and a learning identification method. Inthe adder, the echo estimation signal is subtracted from the microphonedetection signal to thereby calculate the echo-eliminated signal. Notethat in the case where the fixed delay may change depending on the stateof the AV amplifier 300, the fixed delay may be controlled dynamically.

Subsequently, a case where video data and sound data output from thedigital tuner 211 (TV tuner) of the television receiver 200 are viewedand listened to will be described. FIG. 18 is a diagram illustrating acase where video data and sound data output from the digital tuner 211are viewed and listened to. Referring to FIG. 18, during anon-interlocking state with the echo cancellation, a video correspondingto a broadcast signal selected by the digital tuner 211 is displayed onthe TV screen R0. Further, during the non-interlocking state with theecho cancellation, the TV sound is output from the television receiver200 to the AV amplifier 300.

On the other hand, referring to FIG. 18, during an interlocking statewith the echo cancellation, the video corresponding to the broadcastsignal selected by the digital tuner 211 is displayed on the TV screenR0, and the partner display screen R1, the own display screen R2, theSNS screen R3, and the like are also displayed. Further, during theinterlocking state with the echo cancellation, the TV sound and thetelephonic communication destination sound are output from thetelevision receiver 200 to the AV amplifier 300. The AV amplifier 300maintains the sound input as TV, and outputs the TV sound and thetelephonic communication destination sound from the speaker set 350.

Subsequently, a case where video data and sound data output from asource device will be described. FIG. 19 is a diagram illustrating acase where video data and sound data output from the set top box 400used as an example of the source device are viewed and listened to.Referring to FIG. 19, during a non-interlocking state with the echocancellation, a video corresponding to a broadcast signal input from theset top box 400 is displayed on an STB screen R0. Further, during thenon-interlocking state with the echo cancellation, the TV sound isoutput from the set top box 400 to the AV amplifier 300.

Further, referring to FIG. 19, during the non-interlocking state withthe echo cancellation, a sound corresponding to a broadcast signal inputfrom the HDMI terminal 301 to the AV amplifier 300 is output from the AVamplifier 300, and the AV amplifier 300 does not have to transmit thesound to the television receiver 200. In such a case, the AV amplifier300 sets the sound input as the HDMI, and EDID indicating theperformance of the AV amplifier 300 may be shown to the set top box 400.

Note that, in the case where the EDID is shown from the AV amplifier300, the set top box 400 inputs data corresponding to the shown EDID tothe AV amplifier 300. For example, in the case where performanceinformation indicating performance of the television receiver 200 isshown from the AV amplifier 300, the set top box 400 inputs a soundcorresponding to the performance of the television receiver 200 to theAV amplifier 300. On the other hand, in the case where performanceinformation indicating performance of the AV amplifier 300 is shown fromthe AV amplifier 300, the set top box 400 inputs a sound correspondingto the performance of the AV amplifier 300 to the AV amplifier 300.

On the other hand, referring to FIG. 19, during the interlocking statewith the echo cancellation, a video corresponding to a broadcast signalinput from the HDMI terminal 301 to the AV amplifier 300 is displayed onthe STB screen R0, and the partner display screen R1, the own displayscreen R2, the SNS screen R3, and the like are also displayed. Further,during the interlocking state with the echo cancellation, the TV soundand the telephonic communication destination sound input from the HDMIterminal 301 to the AV amplifier 300 are output from the HDMI terminal304 to the television receiver 200.

In such a case, the AV amplifier 300 may show EDID indicatingperformances of the television receiver 200 and the AV amplifier 300 tothe set top box 400. Even if the EDID indicating the performance of theAV amplifier 300 is shown to the set top box 400, in the case where theAV amplifier 300 can convert the signal and can transmit the signal thatsatisfies the EDID shown by the television receiver 200, the AVamplifier 300 can output the sound signal to the television receiver 200without changing the EDID. Further, during the interlocking state withthe echo cancellation, the TV sound and the telephonic communicationdestination sound are output from the television receiver 200 to the AVamplifier 300. The AV amplifier 300 switches the sound input from theHDMI to the TV, and also outputs, from the speaker set 350, the TV soundand the telephonic communication destination sound input from thetelevision receiver 200.

Subsequently, as a reference example, an example of switching betweentwo-screen mode/non-two-screen mode will be described. FIG. 20 is adiagram illustrating an example of switching between general two-screenmode/non-two-screen mode. As shown in FIG. 20, in the non-two-screenmode, a similar operation with the case of the non-interlocking statewith the echo cancellation as shown in FIG. 19 is performed. On theother hand, in the two-screen mode, a video corresponding to a broadcastsignal input from the HDMI terminal 301 to the AV amplifier 300 isdisplayed on the STB screen R01, and a video corresponding to abroadcast signal selected by the digital tuner 211 is displayed on theTV screen R02.

Here, in the case where the TV screen R02 is being focused (rightscreen-focused state), the sound corresponding to the broadcast signalselected by the digital tuner 211 is output from the television receiver200, and the AV amplifier 300 does not have to transmit the sound to thetelevision receiver 200. In such a case, the AV amplifier 300 sets thesound input as the TV, and EDID indicating the performance of the AVamplifier 300 may be kept shown to the set top box 400. Then, thetelevision receiver 200 may set the sound input as the TV tuner.

On the other hand, in the case where the STB screen R01 is being focused(left-screen focused state), the sound corresponding to the broadcastsignal input from the HDMI terminal 301 to the AV amplifier 300 isoutput from the AV amplifier 300, and the AV amplifier 300 does not haveto transmit the sound to the television receiver 200. In such a case,the AV amplifier 300 sets the sound input as the HDMI, and EDIDindicating the performance of the AV amplifier 300 may be shown to theset top box 400. Then, the television receiver 200 may set the soundinput as HDMI1.

Subsequently, an example of information notification performed betweenthe television receiver 200 and the AV amplifier 300 will be described.FIG. 21 is a diagram showing an example of information notificationperformed between the television receiver 200 and the AV amplifier 300.The AV amplifier 300 performs surround processing and various types ofconversion processing (such as frequency conversion and addition ofreverberation) on a sound, and there are cases where nonlinearityappears in the sound and delay is added to the sound. However, whenthose pieces of processing are performed, in the case where the soundoutput from the speaker is detected by the microphone and performing theecho cancellation with respect to the microphone detection signal, theremay occur a defect that it is difficult to perform desired echocancellation.

Accordingly, as shown in FIG. 21, in the case where the CPU 231 startsthe echo cancellation in the television receiver 200, the CPU 231 maytransmit an echo cancellation start request to the AV amplifier 300through the HDMI terminal 201. For the transmission of the echocancellation start request, an HDMI-CEC command may be used. Further, asshown in FIG. 21, in the case where the CPU 321 receives the echocancellation start request through the HDMI terminal 304 in the AVamplifier 300, the CPU 321 may notify the television receiver 200 of asound delay amount through the HDMI terminal 304. The sound delay amountthat the television receiver 200 is notified of may be the sound delayamount that is occurred in the AV amplifier 300.

Further, for dealing with LipSync, the AV amplifier 300 may performprocessing of delaying the audio signal with respect to the videosignal. For example, in the case of changing the sound delay amount forsuch a function, when the echo cancellation is performed without thechanged sound delay amount being detected by the television receiver200, the echo cancellation may not be performed appropriately.Accordingly, the CPU 321 may notify the television receiver 200 of thechanged sound delay amount through the HDMI terminal 304.

Further, in the case where the CPU 321 receives the echo cancellationstart request through the HDMI terminal 304 in the AV amplifier 300, thesound processing circuit 217 may stop sound processing (such as surroundprocessing and various types of conversion processing) that causes thenonlinearity to be appeared. FIG. 22 is a diagram illustrating switchingof sound fields. As shown in FIG. 22, in the non-interlocking state withthe echo cancellation, any sound field may be selected, and in the casewhere the state is switched to the interlocking state with the echocancellation, switching may be performed to the sound field having theecho cancellation effect by conducting a measure such as stopping thesound processing that causes the nonlinearity to be appeared.

Note that, in the case where the CPU 321 receives the echo cancellationstart request through the HDMI terminal 304 in the AV amplifier 300, thesound processing circuit 217 may stop unconditionally the soundprocessing that causes the nonlinearity to be appeared, and may alsostop the sound processing that causes the nonlinearity to be appeared inthe case where a given condition is satisfied. For example, in the casewhere it is difficult for the sound processing circuit 217 to performthe sound processing that causes the nonlinearity to be appeared, thesound processing circuit 217 may stop the sound processing that causesthe nonlinearity to be appeared.

For example, for dealing with LipSync, the AV amplifier 300 may performprocessing of delaying the audio signal with respect to the videosignal. In the case where the delay time of the audio signal withrespect to the video signal is longer than a threshold, the soundprocessing circuit 217 may determine that it becomes difficult toperform surround processing and may stop the sound processing of theecho cancellation. On the other hand, in the case where the delay timeof the audio signal with respect to the video signal is shorter than thethreshold, the sound processing circuit 217 may continue the soundprocessing of the echo cancellation.

Returning to FIG. 21 and the description will be continued. In addition,in the case where the CPU 321 receives the echo cancellation startrequest through the HDMI terminal 304 in the AV amplifier 300, the CPU321 may switch the EDID of the sound signal shown in the set top box400, to thereby pass on the sound from the set top box 400 to thetelevision receiver 200.

As shown in FIG. 21, in the case where the CPU 231 ends the echocancellation in the television receiver 200, the CPU 231 may transmit anecho cancellation end request to the AV amplifier 300 through the HDMIterminal 201. For the transmission of the echo cancellation end request,an HDMI-CEC command may be used. Further, as shown in FIG. 21, in thecase where the CPU 321 receives the echo cancellation end requestthrough the HDMI terminal 304 in the AV amplifier 300, the soundprocessing circuit 217 may return the sound processing to the start. Inaddition, in the case where the CPU 321 receives the echo cancellationend request through the HDMI terminal 304 in the AV amplifier 300, theCPU 321 may return the EDID of the sound signal shown in the set top box400 to the original.

Further, if the echo cancellation is continued in the televisionreceiver 200 after the sound signal is not input from the AV amplifier300 to the television receiver 200 any more, a phase-reversal audiosignal which is reverse to the audio signal to be originally cancelledis transmitted to the communication partner device. Accordingly, in thecase where it has become not possible to play back the sound signal fromthe television receiver 200, the CPU 321 may notify the televisionreceiver 200 of an echo cancellation interrupt request through the HDMIterminal 304.

The case where it is not possible to play back the sound signal from thetelevision receiver 200 may represent the case where the sound inputfrom the AV amplifier 300 is switched to an input other than thetelevision receiver 200, or may represent the case where a mute state isturned on in the AV amplifier 300. Further, the case where it is notpossible to play back the sound signal from the television receiver 200may represent the case where a headphone is connected to the AVamplifier 300, may represent the case where the speaker output in the AVamplifier 300 is turned off, or may represent the case where the speakeroutput is turned to a TV speaker.

Further, the case where it is not possible to play back the sound signalfrom the television receiver 200 may represent the case where the powerof the AV amplifier 300 is turned off, may represent the case where thestate is turned to an automatic sound field correction measurementstate, or may represent the case where the state is turned to a testtone outputting state. Further, the case where it is not possible toplay back the sound signal from the television receiver 200 mayrepresent the case where, when there are HDMI output settings includinga setting capable of performing multiple-device transmission and asetting that prohibits the multiple-device transmission, the soundsignal is not output to the television receiver 200 any more. Further,in the case where it has become possible to input the sound signal tothe television receiver 200, the CPU 321 may notify the televisionreceiver 200 of an echo cancellation restart request through the HDMIterminal 304.

<2-3. Flow of Operation of Communication System>

Subsequently, a flow of an operation of the communication systemaccording to an embodiment of the present disclosure will be described.FIG. 23 is a sequence diagram showing an overall flow of an operation ofthe communication system while a TV is being watched. As shown in FIG.23, let us assume the case where a program selected by a tuner (digitaltuner 211) which is built in the television receiver 200 is beingwatched (Step S201) and the sound input is set to the televisionreceiver 200 in the AV amplifier 300 (Step S202). Subsequently, let usassume that a before-telephonic communication start operation isperformed in the television receiver 200 (Step S203).

In such a case, the television receiver 200 transmits a message <RequestActive Source> in broadcast (Step S204). The AV amplifier 300 switchesthe input of the audio signal to the HDMI terminal 304 or to the TVdedicated terminal (optical input terminal 305, analog audio inputterminal 311, or ARC-compatible HDMI terminal 304) on the basis of themessage <Active Source> transmitted from the television receiver 200 inbroadcast. Subsequently, in the television receiver 200 and the AVamplifier 300, telephonic communication start processing and telephoniccommunication end processing are performed (Step S205). Subsequently,let us assume that an after-telephonic communication end operation isperformed in the television receiver 200 (Step S206).

In such a case, the television receiver 200 transmits a message <ActiveSource> in broadcast (Step S207). The AV amplifier 300 switches theinput of the audio signal to the HDMI terminal 304 or to the TVdedicated terminal (optical input terminal 305 or analog audio inputterminal 311) on the basis of the message <Active Source> transmittedfrom the television receiver 200 in broadcast. Note that in the case ofusing Active Source information which is already grasped, Step S204 andStep S207 may not be performed.

FIG. 24 is a sequence diagram showing an overall flow of an operation ofthe communication system while a STB is being watched. As shown in FIG.24, let us assume the case where the STB is being watched (Step S301),and HDMI1(1.1.0.0) is being selected in the AV amplifier 300 (StepS306). Further, let us assume the case where the power of the set topbox 400 is on (Step S303). Subsequently, let us assume that abefore-telephonic communication start operation is performed in thetelevision receiver 200 (Step S304).

In such a case, the television receiver 200 transmits a message <ActiveSource> in broadcast (Step S305). The AV amplifier 300 switches theinput of the audio signal to the HDMI terminal 304 or to the TVdedicated terminal (optical input terminal 305 or analog audio inputterminal 311) on the basis of the message <Active Source> transmittedfrom the television receiver 200 in broadcast. Subsequently, in thetelevision receiver 200 and the AV amplifier 300, telephoniccommunication start processing and telephonic communication endprocessing are performed (Step S307). Subsequently, let us assume thatan after-telephonic communication end operation is performed in thetelevision receiver 200 (Step S308).

In such a case, the television receiver 200 transmits a message <RoutingChange> in broadcast (Step S309), and receives a message <RoutingInformation>[1.1.0.0] from the AV amplifier 300, to thereby track asignal transmission source (set top box 400) (Step S310). The televisionreceiver 200 transmits a message <Give Device Power Status> to the settop box 400 (Step S311), and receives a message <Report PowerStatus>[On] from the set top box 400 (Step S312).

In this case, in the case where the power state of the set top box 400is determined to be on, the television receiver 200 transmits a message<Set Stream Path>[1.1.0.0] to the set top box 400 (Step S313). The settop box 400 transmits a message <Text View On> or <Image View On> (StepS314). Further, the set top box 400 transmits a message <Active Source>in broadcast (Step S315).

The television receiver 200 switches the input of the audio signal toHDMI1(1.0.0.0) on the basis of the message <Active Source> transmittedfrom the set top box 400 in broadcast (Step S316), and returns to thesource-watching state, which is the state before the start of thetelephonic communication (Step S318). The AV amplifier 300 switches theinput of the audio signal to HDMI1(1.1.0.0) on the basis of the message<Active Source> transmitted from the set top box 400 in broadcast (StepS317). According to such an operation, the state can be returned to theoriginal set top box 400—watching state at the time of ending thetelephonic communication.

FIG. 25 is a sequence diagram showing a flow of an operation of thecommunication system at a time of starting telephonic communication anda time of ending telephonic communication. When the telephoniccommunication is started in the television receiver 200 (Step S401), theCPU 231 transmits an echo cancellation start request to the AV amplifier300 through the HDMI terminal 201 in the television receiver 200 (StepS402). In the case where the CPU 321 receives the echo cancellationstart request through the HDMI terminal 304 in the AV amplifier 300, theCPU 321 performs interlocking operations with the echo cancellation(Step S403), and the CPU 321 transmits a sound delay amount to thetelevision receiver 200 through the HDMI terminal 304 (Step S404).

When the CPU 231 receives the sound delay amount from the AV amplifier300 through the HDMI terminal 201 in the television receiver 200 (StepS402), the CPU 231 reflects the sound delay amount to the echocancellation processing (Step S405). Subsequently, when the telephoniccommunication is ended in the television receiver 200 (Step S406), theCPU 231 transmits an echo cancellation end request to the AV amplifier300 through the HDMI terminal 201 (Step S407). In the case where the CPU321 receives the echo cancellation end request through the HDMI terminal304 in the AV amplifier 300, the CPU 321 returns the interlockingoperations with the echo cancellation to the original states (StepS408).

FIG. 26 is a flowchart showing a flow of an operation of echocancellation processing (with delay amount notification) in the case ofthe external amplifier. First, in the television receiver 200, the CPU231 sets an initial value of an AMP delay (sets an initial value D_(i)as delay time D_(amp) of AMP) (Step S501), sets a system delay (setsdelay time D_(TV)+delay time D_(amp) as system delay D) (Step S502), andinitializes a filter coefficient (Step S503). Subsequently, the CPU 231starts the echo cancellation (Step S504).

When the echo cancellation is started, the adaptive filter 217 bacquires a microphone detection signal obtained by detection by themicrophone 237 (Step S505), and also acquires an audio signal includinga TV sound and a telephonic communication destination sound (Step S506).In the case where the CPU 231 does not receive a sound delay amountD_(amp-new) from the AV amplifier 300 through the HDMI terminal 201(“NO” in Step S507), the CPU 231 proceeds to Step S512. On the otherhand, in the case where the CPU 231 receives the sound delay amountD_(amp-new) from the AV amplifier 300 through the HDMI terminal 201(“YES” in Step S507), the CPU 231 determines whether a given conditionis satisfied.

The given condition may be a condition that D_(amp-new)−D_(amp) islarger than a threshold D_(th-u), or a condition thatD_(amp)−D_(amp-new) is less than a threshold −D_(th-d). In the casewhere the given condition is not satisfied (“NO” in Step S508), the CPU231 proceeds to Step S512. On the other hand, in the case where thegiven condition is satisfied (“YES” in Step S508), the CPU 231 performsupdating of the AMP delay (replaces D_(amp) with D_(amp-new)) (StepS509), performs updating of the system delay (replaces D withD_(TV)+D_(amp)) (Step S510), and initializes the filter coefficient(Step S511).

Subsequently, the adaptive filter 217 b performs echo estimation(generates an echo estimation signal) (Step S512), and the addereliminates an echo estimation signal from the microphone detectionsignal to thereby generate an echo-eliminated signal, and outputs thegenerated echo-eliminated signal (Step S513). Further, the CPU 231updates the filter coefficient (Step S514), and, in the case where thetelephonic communication is not terminated, the processing returns toStep S505, and in the case where the telephonic communication isterminated, the echo cancellation ends (Step S515).

FIG. 27 is a flowchart showing a flow of an operation performed by theAV amplifier 300 at a time of receiving an echo cancellation startrequest. First, in the case where the CPU 321 receives the echocancellation start request through the HDMI terminal 304 in the AVamplifier 300 (Step S601), the CPU 321 sets a request flag (Step S602),and determines whether there is a condition corresponding to any one ofthe conditions disabling the echo cancellation (Step S603). Theconditions disabling the echo cancellation may include a condition thatdisables the playback of the audio signal output from the televisionreceiver 200.

In the case where there is a condition corresponding to any one of theconditions disabling the echo cancellation (“YES” in Step S603), the CPU321 transmits an echo cancellation interrupt request to the televisionreceiver 200 through the HDMI terminal 304 (Step S605). On the otherhand, in the case where there is not a condition corresponding to anyone of the conditions disabling the echo cancellation (“NO” in StepS603), the CPU 321 sets an in-operation flag and starts interlockingoperations with the echo cancellation (Step S604), and the CPU 321transmits a sound delay amount to the television receiver 200 throughthe HDMI terminal 304 (Step S606).

FIG. 28 is a flowchart showing a flow of an operation performed by theAV amplifier 300 at a time of starting interlocking operations with theecho cancellation. As shown in FIG. 28, in the AV amplifier 300, theinterlocking operations with the echo cancellation are started asfollows (Step S701). The AV amplifier 300 stores EDID of a sound signalindicating the AV amplifier 300 (Step S702). The CPU 321 changes theEDID of the sound signal of the AV amplifier 300 for EDID of a soundsignal indicating AV amplifier 300+television receiver 200 (Step S703).The specific EDID for this case represents the EDID that is receivableby the AV amplifier 300 and by the television receiver 200, but the EDIDmay be receivable only by the television receiver 200. Further, when theEDID indicates the performance of the AV amplifier 300, in the casewhere the input signal can be processed in the AV amplifier 300 and canbe converted into a signal in accordance with the EDID indicated by thetelevision receiver 200, it is not necessary to change the EDID.

Further, the AV amplifier 300 stores original sound processing (StepS704). The CPU 321 changes the settings such that the sound processingwithout nonlinear processing is performed (Step S705). Since the settingchange stops the sound processing that causes the nonlinearity to beappeared, switching may be performed to the sound field having the echocancellation effect.

FIG. 29 is a flowchart showing a flow of an operation performed by theAV amplifier 300 at a time of receiving an echo cancellation endrequest. First, in the case where the HDMI reception section 307receives the echo cancellation end request through the HDMI terminal 304in the AV amplifier 300 (Step S801), the CPU 321 clears a request flag(Step S802), and determines whether an in-operation flag is set (StepS803).

In the case where the in-operation flag is not set (“NO” in Step S803),the CPU 321 ends the operation at the time of receiving the echocancellation end request. On the other hand, in the case where thein-operation flag is set (“YES” in Step S803), the CPU 321 clears thein-operation flag and ends the interlocking operations with the echocancellation (Step S804).

FIG. 30 is a flowchart showing a flow of an operation performed by theAV amplifier 300 at a time of ending interlocking operations with theecho cancellation. As shown in FIG. 30, in the AV amplifier 300, theinterlocking operations with the echo cancellation are ended as follows(Step S901). In the AV amplifier 300, the CPU 321 returns the EDID ofthe sound signal of the AV amplifier 300 (changes the EDID for the EDIDindicating the AV amplifier 300) (Step S902). Further, in the AVamplifier 300, the CPU 321 returns the sound processing to the start(changes the settings such that the sound processing with nonlinearprocessing is performed) (Step S903). According to such setting change,the sound processing that may cause the nonlinearity to be appeared isrestarted.

FIG. 31 is a sequence diagram showing a flow of an overall operation ofthe communication system in a case where a sound delay amount is changedin the AV amplifier 300. As shown in FIG. 31, the television receiver200 is in a telephonic communication state (Step S1001), and the AVamplifier 300 is in an interlocking state with the echo cancellation(Step S1002).

Subsequently, in the case where a sound delay amount is changed in theAV amplifier 300 (Step S1004), the CPU 321 transmits the changed sounddelay amount to the television receiver 200 through the HDMI terminal304 (Step S1003). When the CPU 231 receives the changed sound delayamount from the AV amplifier 300 through the HDMI terminal 201 in thetelevision receiver 200, the CPU 231 reflects the changed sound delayamount on the echo cancellation processing.

FIG. 32 is a flowchart showing a flow of an operation performed by theAV amplifier 300 in the case where the sound delay amount is changed inthe AV amplifier. First, in the case where the sound delay amount ischanged in the AV amplifier 300 (Step S1201), the CPU 321 determineswhether an in-operation flag is set (Step S1202). In the case where itis determined that the in-operation flag is not set (“NO” in StepS1202), the operation at the time of the sound delay amount is changedends.

On the other hand, in the case where it is determined that thein-operation flag is set (“YES” in Step S1202), the CPU 321 notifies thetelevision receiver 200 of the sound delay amount through the HDMIterminal 304 (Step S1203), and the operation at the time of the sounddelay amount is changed ends.

FIG. 33 is a sequence diagram showing a flow of an operation of thecommunication system in a case where interlocking with the echocancellation is interrupted by a state change in the AV amplifier 300.As shown in FIG. 33, the television receiver 200 is in a telephoniccommunication state (Step S1301), and the AV amplifier 300 is in aninterlocking state with the echo cancellation (Step S1302).Subsequently, in the case where a reason for echo cancellationinterruption (playback of the audio signal output from the televisionreceiver 200 is disabled) is detected in the AV amplifier 300 (StepS1303), the CPU 321 notifies the television receiver 200 of an echocancellation interrupt request through the HDMI terminal 304 (StepS1304).

When the CPU 231 receives the echo cancellation interrupt request fromthe AV amplifier 300 through the HDMI terminal 201 in the televisionreceiver 200, the CPU 231 interrupts the echo cancellation (Step S1305).Further, in the case where a reason for echo cancellation restart(playback of the audio signal output from the television receiver 200 isenabled) is detected in the AV amplifier 300 (Step S1306), the CPU 321notifies the television receiver 200 of an echo cancellation restartrequest through the HDMI terminal 304 (Step S1307).

When the CPU 231 receives the echo cancellation restart request from theAV amplifier 300 through the HDMI terminal 201 in the televisionreceiver 200, the CPU 231 restarts the echo cancellation (Step S1308).

FIG. 34 is a flowchart showing a flow of an operation of echocancellation processing (with interruption of echo cancellation) in thecase of the external amplifier. First, in the television receiver 200,the CPU 231 sets an initial value of an AMP delay (sets an initial valueD_(i) as delay time D_(amp) of AMP) (Step S1401), sets a system delay(sets delay time D_(TV)+delay time D_(amp) as system delay D) (StepS1402), and initializes a filter coefficient (Step S1403). Subsequently,the CPU 231 starts the echo cancellation (Step S1404).

When the echo cancellation is started, the adaptive filter 217 bacquires a microphone detection signal obtained by detection by themicrophone 237 (Step S1405), and also acquires an audio signal includinga TV sound and a telephonic communication destination sound (StepS1406). Here, in the case where an echo cancellation interrupt requestis received from the AV amplifier 300 through the HDMI terminal 201(“YES” in Step S1407), the A/D conversion section 217 a outputs adigital signal of the microphone detection signal (Step S1308).

On the other hand, in the case where the echo cancellation interruptrequest is not received from the AV amplifier 300 through the HDMIterminal 201 (“NO” in Step S1407), the adaptive filter 217 b performsecho estimation (generates an echo estimation signal) (Step S1409), andthe adder eliminates an echo estimation signal from the microphonedetection signal to thereby generate an echo-eliminated signal, andoutputs the generated echo-eliminated signal (Step S1410). Further, theCPU 231 updates the filter coefficient (Step S1411), and, in the casewhere the telephonic communication is not terminated, the processingreturns to Step S1405, and in the case where the telephoniccommunication is terminated, the echo cancellation ends (Step S1412).

FIG. 35 is a flowchart showing a flow of an operation of the AVamplifier 300 in a case where operation conditions are changed. First,in the case where operation conditions are changed in the AV amplifier300 (Step S1501), the CPU 321 determines whether a request flag is set(Step S1502). In the case where the request flag is not set (“NO” inStep S1502), the CPU 321 ends the operation at the time of changing theoperation conditions. On the other hand, in the case where the requestflag is set (“YES” in Step S1502), the CPU 321 determines whether thereis a condition corresponding to any one of the conditions disabling theecho cancellation (Step S1503).

In the case where there is not a condition corresponding to any one ofthe conditions disabling the echo cancellation (“NO” in Step S1503), theCPU 321 determines whether an in-operation flag is set (Step S1504). Inthe case where the in-operation flag is set (“YES” in Step S1504), theCPU 321 ends the operation at the time of changing the operationconditions. On the other hand, in the case where the in-operation flagis not set (“NO” in Step S1504), the CPU 321 sets the in-operation flagand starts interlocking operations with the echo cancellation (StepS1505), and the CPU 321 transmits an echo cancellation restart requestto the television receiver 200 through the HDMI terminal 304 (StepS1506).

On the other hand, in the case where there is a condition correspondingto any one of the conditions disabling the echo cancellation (“YES” inStep S1503), the CPU 321 determines whether an in-operation flag is set(Step S1507). In the case where the in-operation flag is not set (“NO”in Step S1507), the CPU 321 ends the operation at the time of changingthe operation conditions. On the other hand, in the case where thein-operation flag is set (“YES” in Step S1507), the CPU 321 clears thein-operation flag and ends the interlocking operations with the echocancellation (Step S1508), and the CPU 321 transmits an echocancellation interrupt request to the television receiver 200 throughthe HDMI terminal 304 (Step S1509).

FIG. 36 is a flowchart showing a flow of an operation of determininginterlock capability with echo cancellation performed in the AVamplifier 300. As shown in FIG. 36, in the AV amplifier 300, thedetermination of interlock capability with the echo cancellation isstarted as follows (Step S1601). In the case where an audio signal fromthe television receiver 200 is not played back, the CPU 321 maydetermine that the interlocking with the echo cancellation is incapable,and in the case where the audio signal from the television receiver 200is played back, the CPU 321 may determine that the interlocking with theecho cancellation is capable.

As shown in FIG. 36, for example, in the case where the sound input isnot TV (“NO” in Step S1602), the CPU 321 may determine that theinterlocking with the echo cancellation is incapable. On the other hand,in the case where the sound input is TV (“YES” in Step S1602), the CPU321 may proceed to Step S1603. Further, in the case where the mute stateis on (“NO” in Step S1603), the CPU 321 may determine that theinterlocking with the echo cancellation is incapable. On the other hand,in the case where the mute state is off (“YES” in Step S1603), the CPU321 may proceed to Step S1604.

Further, in the case where headphones are connected to the AV amplifier300 (“NO” in Step S1604), the CPU 321 may determine that theinterlocking with the echo cancellation is incapable. On the other hand,in the case where the headphones are unconnected to the AV amplifier 300(“YES” in Step S1604), the CPU 321 may determine that the interlockingwith the echo cancellation is capable.

FIG. 37 is a sequence diagram showing an operation example of thecommunication system in a case where sound output is changed from thetelevision receiver 200 to the AV amplifier 300 during telephoniccommunication. As shown in FIG. 37, the television receiver 200 is in atelephonic communication state (Step S1701), and the AV amplifier 300 isin a mute ON state (Step S1702). Here, in the case where the soundoutput is changed from the television receiver 200 to the AV amplifier300, in the television receiver 200, the CPU 231 transmits a message<System Audio Mode Request>[On] to the AV amplifier 300 through the HDMIterminal 201 (Step S1703).

When the CPU 321 receives the message in the AV amplifier 300, the CPU321 makes the AV amplifier 300 to be in a mute OFF state (Step S1704).In the mute OFF state, the audio is output from the speaker set 350.Subsequently, in the television receiver 200, the CPU 231 transmits amessage <Give Audio Status> to the AV amplifier 300 through the HDMIterminal 201 (Step S1705).

When the CPU 321 receives the message in the AV amplifier 300, the CPU321 transmits a message <Report Audio Status>[Mute Off/Volume] includinga mute state and a volume to the television receiver 200 through theHDMI terminal 304 (Step S1706). The CPU 231 receives the message fromthe AV amplifier 300 through the HDMI terminal 201 in the televisionreceiver 200, and when confirming that the AV amplifier 300 is in adesired mute state, the CPU 231 makes the television receiver 200 to bein a mute ON state (Step S1707). In the mute ON state, the audio is notoutput from the speaker 219.

Subsequently, in the television receiver 200, the CPU 231 transmits anecho cancellation start request to the AV amplifier 300 through the HDMIterminal 201 (Step S1708). In the case where the CPU 321 receives theecho cancellation start request through the HDMI terminal 304 in the AVamplifier 300, the CPU 321 performs interlocking operations with theecho cancellation (Step S1709), and transmits a sound delay amount tothe television receiver 200 through the HDMI terminal 304 (Step S1710).When the CPU 231 receives the sound delay amount from the AV amplifier300 through the HDMI terminal 201 in the television receiver 200, theCPU 231 reflects the sound delay amount and the volume on the echocancellation processing (Step S1711).

FIG. 38 is a sequence diagram showing an operation example of thecommunication system in a case where sound output is changed from the AVamplifier 300 to the television receiver 200 during telephoniccommunication. As shown in FIG. 38, the television receiver 200 is in atelephonic communication state and in a mute ON state mute ON state(Step S1801), and the AV amplifier 300 is in a state of performinginterlocking operations (Step S1802). Here, in the case where the soundoutput is changed from the AV amplifier 300 to the television receiver200, in the television receiver 200, the CPU 231 transmits a message<System Audio Mode Request>[Off] to the AV amplifier 300 through theHDMI terminal 201 (Step S1803).

When the CPU 321 receives the message in the AV amplifier 300, the CPU321 makes the AV amplifier 300 to be in a mute ON state (Step S1804). Inthe mute ON state, the audio is not output from the speaker set 350.Subsequently, in the AV amplifier 300, the CPU 321 transmits a message<Set System Audio Mode>[Off] through the HDMI terminal 304 in broadcast(Step S1805), and cancels the interlocking operations (Step S1807).

When the CPU 231 receives the message from the AV amplifier 300 throughthe HDMI terminal 201 in the television receiver 200, the CPU 231 makesthe television receiver 200 to be in the mute OFF state (Step S1808). Inthe mute OFF state, the audio is output from the speaker 219.Subsequently, in the television receiver 200, the CPU 231 transmits amessage <Give Audio Status> to the AV amplifier 300 through the HDMIterminal 201 (Step S1809).

When the CPU 321 receives the message in the AV amplifier 300, the CPU321 transmits a message <Report Audio Status>[Mute Off/Volume] includinga mute state and a volume to the television receiver 200 through theHDMI terminal 304 (Step S1810). When the CPU 231 receives the messagefrom the AV amplifier 300 through the HDMI terminal 201 in thetelevision receiver 200, the CPU 231 reflects the volume on the echocancellation processing (Step S1811) and the television receiver 200confirms that the AV amplifier 300 is in a desired mute state.

FIG. 39 is a sequence diagram showing an operation example of thecommunication system in a case where a volume of the AV amplifier 300 ischanged. As shown in FIG. 39, the AV amplifier 300 is in a state ofperforming interlocking operations (Step S1902). Here, in the case wherean operation of turning up the volume is performed in the televisionreceiver 200 (Step S1901), in the television receiver 200, the CPU 231transmits a message <User Control Pressed>[Volume Up] to the AVamplifier 300 through the HDMI terminal 201 (Step S1903).

When the CPU 321 receives the message in the AV amplifier 300, the CPU321 turns up the volume (Step S1904). Subsequently, in the AV amplifier300, the CPU 321 transmits a message <Report Audio Status>[MuteOff/Volume] through the HDMI terminal 304 in broadcast (Step S1905).When the CPU 231 receives the message from the AV amplifier 300 throughthe HDMI terminal 201 in the television receiver 200, the CPU 231reflects the volume and the mute state on the echo cancellationprocessing (Step S1906).

When the operation of turning up the volume is terminated in thetelevision receiver 200, in the television receiver 200, the CPU 231transmits a message <User Control Released> to the AV amplifier 300through the HDMI terminal 201 (Step S1907). When the CPU 321 receivesthe message in the AV amplifier 300, the operation of turning up thevolume ends.

FIG. 40 is a flowchart showing a flow of an operation of echocancellation processing (with volume notification) in the case of theexternal amplifier. First, in the television receiver 200, the CPU 231sets an initial value of an AMP delay (sets an initial value D_(i) asdelay time D_(amp) of AMP) (Step S2001), sets a system delay (sets delaytime D_(TV)+delay time D_(amp) as system delay D) (Step S2002), andinitializes a filter coefficient (Step S2003). Subsequently, the CPU 231starts the echo cancellation (Step S2004).

When the echo cancellation is started, the adaptive filter 217 bacquires a microphone detection signal obtained by detection by themicrophone 237 (Step S2005), and also acquires an audio signal includinga TV sound and a telephonic communication destination sound (StepS2006). Here, in the case where the AV amplifier 300 performsnotification of a volume V_(amp) through the HDMI terminal 201 (“YES” inStep S2007), when the volume V_(amp) is less than a threshold V_(th)(“YES” in Step S2008), the A/D conversion section 217 a outputs adigital signal of the microphone detection signal (Step S2009).

On the other hand, in the case where the AV amplifier 300 does notperform notification of the volume V_(amp) through the HDMI terminal 201(“NO” in Step S2007), and the volume V_(amp) is more than or equal tothe threshold V_(th) (“YES” in Step S2008), the adaptive filter 217 bperforms echo estimation (generates an echo estimation signal) (StepS2010), and the adder eliminates an echo estimation signal from themicrophone detection signal to thereby generate an echo-eliminatedsignal, and outputs the generated echo-eliminated signal (Step S2011).Further, the CPU 231 updates the filter coefficient (Step S2012), and,in the case where the telephonic communication is not terminated, theprocessing returns to Step S2005, and in the case where the telephoniccommunication is terminated, the echo cancellation ends (Step S2013).

3. Conclusion

As described above, according to an embodiment of the presentdisclosure, there is provided an audio device including a controlsection configured to cause an audio signal to be output, the audiosignal including a sound signal obtained through playback of content anda sound signal received from a communication partner device, and a soundprocessing section configured to generate an elimination signal, theelimination signal being obtained by eliminating a given sound signalfrom a microphone detection signal, the microphone detection signalrepresenting the audio signal propagating and being obtained bydetection by a microphone, in which the control section causes thecommunication partner device to transmit the elimination signal.According to such a configuration, a conversation carried out with apartner while listening to a content playback sound can be made morecomfortable.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

Further, the respective steps included in the communication system ofthe present specification are not necessarily processed in a time-seriesorder in accordance with the flowcharts and the sequence diagrams. Forexample, the respective steps included in the operation of thecommunication system may be processed in different order from theflowcharts and the sequence diagrams, or may be processed in a parallelmanner.

Further, it is also possible to create a computer program for causinghardware such as the CPU, the ROM, and the RAM, which are built in thetelevision receiver 200, to exhibit substantially the same functions asthe respective functions of the television receiver 200 described above.Further, there is also provided a storage medium having the computerprogram stored therein.

Further, it is also possible to create a computer program for causinghardware such as the CPU, the ROM, and the RAM, which are built in theAV amplifier 300, to exhibit substantially the same functions as therespective functions of the AV amplifier 300 described above. Further,there is also provided a storage medium having the computer programstored therein.

Further, the effects described in the present specification are merelyillustrative or exemplified effects, and are not limitative. That is,with or in the place of the above effects, there may be achieved theeffects described in this specification and/or other effects that areclear to those skilled in the art based on the description of thisspecification.

Additionally, the present technology may also be configured as below.

(1) An audio device including:

a control section configured to cause an audio signal to be output, theaudio signal including a sound signal obtained through playback ofcontent and a sound signal received from a communication partner device;and

a sound processing section configured to generate an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone,

wherein the control section causes the communication partner device totransmit the elimination signal.

(2) The audio device according to (1),

wherein the control section causes another audio device to transmit theaudio signal.

(3) The audio device according to (2),

wherein the sound processing section generates the elimination signal onthe basis of a sound delay amount received from the another audiodevice.

(4) The audio device according to (2) or (3),

wherein the control section causes the another audio device to transmitgeneration start of the elimination signal when starting the generationof the elimination signal.

(5) The audio device according to (4),

wherein the control section causes the another audio device to transmitgeneration end of the elimination signal when ending the generation ofthe elimination signal.

(6) The audio device according to any one of (2) to (5),

wherein, in a case where the control section receives from the anotheraudio device an interrupt request for interruption of the generation ofthe elimination signal, the control section interrupts the generation ofthe elimination signal.

(7) The audio device according to any one of (2) to (6),

wherein the sound processing section generates the elimination signal onthe basis of a volume received from the another audio device.

(8) The audio device according to (1),

wherein the control section causes the audio signal to be output from aspeaker included in the audio device.

(9) The audio device according to any one of (1) to (8),

wherein the given sound signal is calculated on the basis of an adaptivefilter coefficient learned by a given adaptive signal processingalgorithm.

(10) A sound processing method including:

causing an audio signal to be output, the audio signal including a soundsignal obtained through playback of content and a sound signal receivedfrom a communication partner device;

generating an elimination signal obtained by eliminating a given soundsignal from a microphone detection signal, which is the audio signalthat is propagated and detected by a microphone; and

causing, by a processor, the communication partner device to transmitthe elimination signal.

(11) A sound processing program for causing a computer to function as anaudio device, the audio device including

a control section configured to cause an audio signal to be output, theaudio signal including a sound signal obtained through playback ofcontent and a sound signal received from a communication partner device,and

a sound processing section configured to generate an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone,

wherein the control section causes the communication partner device totransmit the elimination signal.

(12) An audio device including:

a control section configured to, when an audio signal including a soundsignal obtained through playback of content and a sound signal receivedfrom a communication partner device is input from another audio device,cause the audio signal to be output from a speaker,

wherein the another audio device generates an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone.

(13) The audio device according to (12),

wherein, when the sound signal obtained through the playback of contentis input, the control section outputs the sound signal to the anotheraudio device.

(14) The audio device according to (12) or (13),

wherein, in a case where the control section is not capable ofoutputting the sound signal obtained through the playback of content tothe another audio device, the control section causes the another audiodevice to transmit an interrupt request for interruption of thegeneration of the elimination signal.

(15) The audio device according to any one of (12) to (14),

wherein, in a case where the control section receives generation startof the elimination signal from the another audio device, the controlsection starts a given interlocking operation that interlocks with thegeneration of the elimination signal.

(16) The audio device according to (15),

wherein, in a case where the control section receives generation end ofthe elimination signal from the another audio device, the controlsection ends the given interlocking operation.

(17) A sound output method including:

causing, when an audio signal including a sound signal obtained throughplayback of content and a sound signal received from a communicationpartner device is input from another audio device, the audio signal tobe output from a speaker,

wherein the another audio device generates an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone.

(18) A sound output program for causing a computer to function as anaudio device, the audio device including

a control section configured to, when an audio signal including a soundsignal obtained through playback of content and a sound signal receivedfrom a communication partner device is input from another audio device,cause the audio signal to be output from a speaker,

wherein the another audio device generates an elimination signalobtained by eliminating a given sound signal from a microphone detectionsignal, which is the audio signal that is propagated and detected by amicrophone.

1.-18. (canceled)
 19. An audio processing apparatus that outputs a firstaudio signal including audio content and a second audio signal receivedfrom a communication apparatus, comprising: sound processing circuitrythat receives a microphone detection signal comprising the first audiosignal and the second audio signal and generates an elimination signalthat is used to remove a predetermined audio signal from the microphonedetection signal to produce an echo-eliminated signal, a transmitterthat transmits the echo-eliminated signal to the communication apparatusupon generation of the echo-eliminated signal by the sound processingcircuitry, and an output for producing audible sound comprising thefirst audio signal and the second audio signal.
 20. The audio processingapparatus of claim 19, wherein the sound processing circuitry generatesthe elimination signal based on an amount of delay that occurs betweenthe output generating the audible sound and detection of the microphonedetection signal.
 21. The audio processing apparatus of claim 19,wherein transmission of the echo-eliminated signal to the communicationapparatus stops upon the sound processing circuitry ending generation ofthe elimination signal.
 22. The audio processing apparatus of claim 19,wherein generation of the elimination signal is interrupted upon receiptof a suspend request.
 23. The audio processing apparatus of claim 19,wherein the sound processing circuitry generates the elimination signalbased on volume of the audible sound at the output.
 24. The audioprocessing apparatus of claim 23, wherein the output comprises aspeaker.
 25. The audio processing apparatus of claim 19, wherein theelimination signal is computed based on an adaptive filter coefficientlearned by a predetermined adaptive-signal-processing algorithm.
 26. Theaudio processing apparatus of claim 19, wherein the elimination signalcomprises an echo estimation signal and the sound processing circuitrycomprises an adaptive filter that generates the echo estimation signal.27. The audio processing apparatus of claim 26, wherein the soundprocessing circuitry further includes an adder that computes theecho-eliminated signal based on the echo estimation signal and themicrophone detection signal.
 28. The audio processing apparatus of claim27, wherein the microphone detected signal comprises a digitalrepresentation of the first audio signal and the second audio signaldetected by a microphone within range of the audible sound produced bythe output.
 29. An audio processing method comprising: receiving amicrophone detection signal detected by a microphone, the microphonedetection signal comprising a first audio signal and a second audiosignal; generating an elimination signal that is used to remove apredetermined audio signal from the microphone detection signal toproduce an echo-eliminated signal; transmitting the echo-eliminatedsignal to a communication apparatus upon generation of theecho-eliminated signal; and generating audible sound comprising thefirst audio signal and the second audio signal.
 30. A non-transitorycomputer readable medium storing instructions that, when executed by aprocessing device, cause the processing device to process executableinstructions to perform a method, the method comprising: receiving amicrophone detection signal detected by a microphone, the microphonedetection signal comprising a first audio signal and a second audiosignal; generating an elimination signal that is used to remove apredetermined audio signal from the microphone detection signal toproduce an echo-eliminated signal; transmitting the echo-eliminatedsignal to a communication apparatus upon generation of theecho-eliminated signal; and generating audible sound comprising thefirst audio signal and the second audio signal.
 31. The non-transitorycomputer readable medium of claim 30, wherein generating the eliminationsignal further comprises generating the elimination signal based on anamount of delay that occurs between the output generating the audiblesound and detection of the microphone detection signal.
 32. Thenon-transitory computer readable medium of claim 30, whereintransmitting the echo-eliminated signal to the communication apparatusstops upon the sound processing circuitry ending generation of theelimination signal.
 33. The non-transitory computer readable medium ofclaim 30, wherein generating the elimination signal is interrupted uponreceipt of a suspend request.
 34. The non-transitory computer readablemedium of claim 30, wherein generating the elimination signal furthercomprises generating the elimination signal based on volume of theaudible sound at the output.
 35. The non-transitory computer readablemedium of claim 30, wherein generating audible sound further comprisesgenerating audible sound through a speaker.
 36. The non-transitorycomputer readable medium of claim 30, wherein generating the eliminationsignal further comprises computing the elimination signal based on anadaptive filter coefficient learned by a predeterminedadaptive-signal-processing algorithm.